diff --git a/src/esnb/core/CaseExperiment.py b/src/esnb/core/CaseExperiment.py
index 86c229b..c2a3030 100644
--- a/src/esnb/core/CaseExperiment.py
+++ b/src/esnb/core/CaseExperiment.py
@@ -1,3 +1,5 @@
+import warnings
+
 import yaml
 
 try:
@@ -28,6 +30,11 @@ def __init__(
         self.source = source
         self.catalog = catalog
 
+        warnings.warn(
+            "`CaseExperiment` is deprecated and will be REMOVED on 18-Aug-25. Use `CaseExperiment2` instead",
+            DeprecationWarning,
+        )
+
         # TODO - make conformant to MDTF keys where possible
         if source == "dora":
             if verbose:
diff --git a/src/esnb/core/CaseGroup.py b/src/esnb/core/CaseGroup.py
index ad921bc..7723261 100644
--- a/src/esnb/core/CaseGroup.py
+++ b/src/esnb/core/CaseGroup.py
@@ -1,5 +1,6 @@
 import os
 import tempfile
+import warnings
 
 import xarray as xr
 
@@ -20,6 +21,11 @@ def __init__(
         source="dora",
         verbose=True,
     ):
+        warnings.warn(
+            "`CaseGroup` is deprecated and will be REMOVED on 18-Aug-25. Use `CaseGroup2` instead",
+            DeprecationWarning,
+        )
+
         self.locations = [locations] if not isinstance(locations, list) else locations
         if len(self.locations) > 1:
             assert concat_dim is not None, (