Some authors regard gambling as an addiction. Detailed psychiatric examination revealed obsessive-compulsive syndrome in this patient. He was treated systematically with individual psychotherapy and sertraline from low doses up to the maximal dose (i.e. about 200 mg daily). A complete remission of the obsessive-compulsive syndrome was achieved. A number of indirect proofs demonstrate a significant role of sertraline in the aetiotogy of obsessive-compulsive syndrome. The most important evidence is the effectiveness of the drug from the group of selective inhibitors of serotonin central reuptake (SI-5HT) in the treatment of obsessive compulsive syndrome. Sertraline is safe and effective in the treatment of obsessive-compulsive syndrome. Drug doses ranged from 50 to 200 mg daily.