Although there are few studies on the treatment of schizophrenia with testosterone, several indirect findings have suggested testosterone as a possible treatment modality for schizophrenia. To explore the therapeutic effect of testosterone augmentation of antipsychotic medication on symptoms in male patients with schizophrenia, the authors performed a placebo-controlled, double-blind trial on 30 schizophrenic men, using either 5 g of 1% testosterone gel (Testogel; Besins Iscovesco, Paris, France) or a placebo added to a fixed dosage of antipsychotic medication over a period of 4 weeks with a 2-week washout period. In addition, to get additional information about the involvement of these reproductive hormones after testosterone augmentation, the authors evaluated several hormones such as total testosterone, free testosterone, dehydroepiandrosterone sulfate, estradiol, and prolactin. Results indicated a significant improvement of negative symptoms in both the last observation carried forward and the completer analyses and a nonsignificant trend for the improvement of depressive symptoms in completers. There were no significant changes in serum hormone levels except total and free testosterone. The findings of this study suggest that testosterone augmentation may be a potential therapeutic strategy in patients with schizophrenia.