diff --git a/jax/lax/lax_control_flow.py b/jax/lax/lax_control_flow.py
index <HASH>..<HASH> 100644
--- a/jax/lax/lax_control_flow.py
+++ b/jax/lax/lax_control_flow.py
@@ -621,6 +621,17 @@ def cond(*args, **kwargs):
 
   Pred must be a scalar type.
 
+  Note that true_fun/false_fun may not need to refer to an `operand` to compute
+  their result, but one must still be provided to the `cond` call and be
+  accepted by both the branch functions, e.g.:
+
+      jax.lax.cond(
+          get_predicate_value(),
+          lambda _: 23,
+          lambda _: 42,
+          operand=None)
+
+
   Arguments:
     pred: Boolean scalar type, indicating which branch function to
       apply. Collections (list, tuple) are not supported.
Clarify docs on jax.lax.cond. (#<I>)