Myxedematous psychosis was first described in 1979 by Pr Asher, it is a rare diagnosis associating an acute psychosis, a rhabdomyolysis whose etiology is hypothyroidism. We report the case of a 32-year-old patient followed for 6 years for schizophrenia, who had not had any treatment for 3 years, and was admitted with an acute psychotic attack consisting of delusions of persecution. The examination revealed an oedematose syndrome, deep hypothyroidism, and high creatine phosphokinase. The treatment was the correction of the hypothyroidism associated with a short psychogenic treatment with a favorable evolution after 1 month of treatment with regression of the psychiatric picture.