WASHINGTON (AP) _ CIA Director William J. Casey remained in stable condition at Georgetown University Hospital while recuperating from brain surgery, a hospital spokesman said Monday.

''There has been no change,'' said public relations director Gary Krull. ''He is still in stable and recovering condition. He is still in and out of bed and sitting in a chair when he feels like it. He is still fully conscious.''

Asked if Casey was able to speak, Krull said, ''I don't know.''

Casey underwent surgery Dec. 18 for removal of a brain tumor.

President Reagan was asked about Casey's condition Monday as the president boarded Air Force One for a flight from Los Angeles to the desert resort of Palm Springs.

''I don't have any new information on it,'' Reagan told reporters.