The limited effect of current antipsychotics on the schizophrenia symptoms has led to the search for novel drugs that can potentiate the treatment of this disorder. Minocycline is an antibiotic of the tetracycline group, with effi- cacy in different neurological diseases. Various findings from animal and human studies suggest that minocycline has possible advantages for the treatment of schizophrenia, including case reports of beneficial effects in catatonic schizophrenia. The current study investigated the effects of min- ocycline as adjuvant therapy in three patients with recent onset paranoid schizophrenia in use of a stable dose of olanzapine for more than four months (15, 20 and 20 mg/day respectively).