diff --git a/pyproj/_crs.pyx b/pyproj/_crs.pyx
index 4e3f28c2..0209ee85 100644
--- a/pyproj/_crs.pyx
+++ b/pyproj/_crs.pyx
@@ -569,7 +569,13 @@ cdef class CoordinateSystem(_CRSParts):
     """
     .. versionadded:: 2.2.0
 
-    Coordinate System for CRS
+    Coordinate System for CRS.
+
+    .. note:: | WKT and CRS are not compatible as standalone element (see `OSGeo/PROJ#1819 <https://github.com/OSGeo/PROJ/issues/1819>`_ for more details).
+              | We recommend using `to_json`/`from_json` for the import.
+
+    .. note:: | WKT does not work on import for CoordinateSystem.
+              | PROJ JSON is preferred.
 
     Attributes
     ----------