Current data reveal that aripiprazole is associated with minimal weight gain. Patients who were stable and had gained excessive weight during olanzapine treatment were switched to aripiprazole. The objective was to evaluate the effect of this switch on body weight.

The effective dosage of aripiprazole 15 mg/day was started while olanzapine 10 mg/day was gradually tapered and stopped.

Case 1. M.A, a 49 -year old woman, had a history of bipolar disorder. She was treated with olanzapine and had gained 14 Kgr while taking aripiprazole, she had lost 9 kgr.

Case 2. Ms B, a 34-year-old woman had a history of schizophrenia. She had been treated with olanzapine and gained 10 kgr. She took aripiprazole and lost 4 Kgr.

Case 3. Mr C, a 45-year-old man, had a history of delusional disorder. He was treated with olanzapine and gained 12 kgr. He took aripiprazole and lost 5 Kgr

Case 4. Mr D, a 25-year-old man, had a diagnosis of schizotypal personality disorder. He was treated with olanzapine and gained 9 kgr, while taking aripiprazole, he had lost 8 Kgr

Case 5. Mr E, a 40-year-old woman, had a diagnosis of schizophrenia. She was treated with olanzapine and had gained 14 kgr, while taking aripiprazole, she had lost 6 Kgr

This study suggests that switching treatment to aripiprazole may be a useful strategy for patients who have gained excessive weight with olanzapine.