High cortisol level in endogenous Cushing’s syndrome suppresses the immune system and after treatment there may be an over activity of immune reaction leading to autoimmune diseases mostly thyroid and rheumatologic disorders. This is the second reported case of multiple sclerosis developing after treatment of Cushing’s syndrome. A 42-year old man is reported who presented with bone fracture and osteoporosis and diagnosed with Cushing’s disease. Six months after surgical treatment of his pituitary adenoma, he developed progressive multiple sclerosis. We conclude that after treatment of endogenous Cushing’s syndrome, the patients should be watched for development of autoimmune disorders including those affecting the central nervous system.