diff --git a/math_explorer_gui/src/tabs/clinical_trials/mod.rs b/math_explorer_gui/src/tabs/clinical_trials/mod.rs
index c6c52b90..022df4db 100644
--- a/math_explorer_gui/src/tabs/clinical_trials/mod.rs
+++ b/math_explorer_gui/src/tabs/clinical_trials/mod.rs
@@ -1,9 +1,11 @@
 use crate::tabs::ExplorerTab;
 use eframe::egui;
 
+pub mod randomization;
 pub mod sample_size;
 pub mod survival;
 
+use randomization::RandomizationTool;
 use sample_size::SampleSizeCalculatorTool;
 use survival::SurvivalAnalysisTool;
 
@@ -27,6 +29,7 @@ impl Default for ClinicalTrialsTab {
             tools: vec![
                 Box::new(SurvivalAnalysisTool::default()),
                 Box::new(SampleSizeCalculatorTool::default()),
+                Box::new(RandomizationTool::default()),
             ],
             selected_tool_index: 0,
         }
diff --git a/math_explorer_gui/src/tabs/clinical_trials/randomization.rs b/math_explorer_gui/src/tabs/clinical_trials/randomization.rs
new file mode 100644
index 00000000..abe7ceaf
--- /dev/null
+++ b/math_explorer_gui/src/tabs/clinical_trials/randomization.rs
@@ -0,0 +1,124 @@
+use super::ClinicalTrialsTool;
+use eframe::egui;
+use math_explorer::applied::clinical_trials::design::{AllocationStrategy, BlockRandomizer, Group, SimpleRandomizer};
+
+#[derive(PartialEq)]
+enum RandomizationMethod {
+    Simple,
+    Block,
+}
+
+pub struct RandomizationTool {
+    method: RandomizationMethod,
+    n_subjects: usize,
+    block_size: usize,
+    assignments: Vec<Group>,
+    error_message: Option<String>,
+}
+
+impl Default for RandomizationTool {
+    fn default() -> Self {
+        Self {
+            method: RandomizationMethod::Simple,
+            n_subjects: 20,
+            block_size: 4,
+            assignments: Vec::new(),
+            error_message: None,
+        }
+    }
+}
+
+impl ClinicalTrialsTool for RandomizationTool {
+    fn name(&self) -> &'static str {
+        "Randomization"
+    }
+
+    fn show(&mut self, ctx: &egui::Context) {
+        egui::CentralPanel::default().show(ctx, |ui| {
+            ui.vertical(|ui| {
+                ui.heading("Subject Randomization");
+                ui.separator();
+
+                ui.horizontal(|ui| {
+                    ui.label("Randomization Method:");
+                    ui.radio_value(&mut self.method, RandomizationMethod::Simple, "Simple");
+                    ui.radio_value(&mut self.method, RandomizationMethod::Block, "Block");
+                });
+
+                ui.add(egui::Slider::new(&mut self.n_subjects, 1..=500).text("Total Subjects"));
+
+                if self.method == RandomizationMethod::Block {
+                    ui.add(egui::Slider::new(&mut self.block_size, 2..=20).step_by(2.0).text("Block Size"));
+                }
+
+                if ui.button("Generate Assignments").clicked() {
+                    self.error_message = None;
+                    self.assignments.clear();
+
+                    let mut rng = rand::thread_rng();
+
+                    match self.method {
+                        RandomizationMethod::Simple => {
+                            let randomizer = SimpleRandomizer;
+                            match randomizer.assign(&mut rng, self.n_subjects) {
+                                Ok(assignments) => self.assignments = assignments,
+                                Err(e) => self.error_message = Some(e.to_string()),
+                            }
+                        }
+                        RandomizationMethod::Block => {
+                            match BlockRandomizer::new(self.block_size) {
+                                Ok(randomizer) => {
+                                    match randomizer.assign(&mut rng, self.n_subjects) {
+                                        Ok(assignments) => self.assignments = assignments,
+                                        Err(e) => self.error_message = Some(e.to_string()),
+                                    }
+                                }
+                                Err(e) => self.error_message = Some(e.to_string()),
+                            }
+                        }
+                    }
+                }
+
+                if let Some(err) = &self.error_message {
+                    ui.colored_label(egui::Color32::RED, format!("Error: {}", err));
+                }
+
+                ui.separator();
+
+                if !self.assignments.is_empty() {
+                    ui.heading("Assignments");
+
+                    // Count treatments vs controls
+                    let treatment_count = self.assignments.iter().filter(|&&g| g == Group::Treatment).count();
+                    let control_count = self.assignments.iter().filter(|&&g| g == Group::Control).count();
+
+                    ui.label(format!("Treatment Group: {} subjects", treatment_count));
+                    ui.label(format!("Control Group: {} subjects", control_count));
+
+                    ui.separator();
+
+                    egui::ScrollArea::vertical().show(ui, |ui| {
+                        egui::Grid::new("assignments_grid")
+                            .striped(true)
+                            .show(ui, |ui| {
+                                ui.label(egui::RichText::new("Subject ID").strong());
+                                ui.label(egui::RichText::new("Assigned Group").strong());
+                                ui.end_row();
+
+                                for (i, group) in self.assignments.iter().enumerate() {
+                                    ui.label(format!("{:03}", i + 1));
+
+                                    let group_text = match group {
+                                        Group::Treatment => egui::RichText::new("Treatment").color(egui::Color32::LIGHT_BLUE),
+                                        Group::Control => egui::RichText::new("Control").color(egui::Color32::LIGHT_GREEN),
+                                    };
+                                    ui.label(group_text);
+                                    ui.end_row();
+                                }
+                            });
+                    });
+                }
+            });
+        });
+    }
+}
diff --git a/todo_gui.md b/todo_gui.md
index 4a0fff5a..66817543 100644
--- a/todo_gui.md
+++ b/todo_gui.md
@@ -114,7 +114,7 @@ This document outlines the roadmap for integrating the various modules of the `m
 *   **Features:**
     *   [x] **Survival Curves:** Kaplan-Meier plot generator.
     *   [x] **Sample Size Calculator:** Form inputs for $\alpha$, $\beta$, and effect size.
-    *   [ ] **Randomization:** Interactive subject allocation tool.
+    *   [x] **Randomization:** Interactive subject allocation tool.
 
 ### 4.3 Favoritism (Satirical)
 *   **Module:** `applied::favoritism`