Some case reports have shown that patients suffering from obsessive-compulsive disorder can be effectively treated with anti-androgenic pharmacological agents with various modes of action. The most effective group of such agents is the long-acting analogues of the gonadotropin-releasing hormone. This investigation was undertaken in order to further elucidate the possibility of using such powerful anti-androgenic agents in the treatment of obsessive-compulsive disorder. Six male patients, all suffering from therapy-resistant obsessive-compulsive disorder, were included in a 48 weeks open-label trial of the long-acting GnRH-analogue triptorelin. Every other week, the patients rated the severity of obsessive-compulsive disorder symptoms by means of a visual analogue scale. During the course of the trial, five out of six patients experienced a considerable improvement. The finding gives further support to the contention that anti-androgenic agents are effective in the treatment of obsessive-compulsive disorder.