This study aimed to evaluate the effect of citalopram in patients with refractory obsessive-compulsive disorder (OCD) which had not responded to previous antiobsessional treatments. Eighteen patients were selected for this study: they had been suffering from OCD, according to DSM-IV criteria, for at least 2 years and had various comorbid disorders. All had been treated with serotonin reuptake inhibitors at adequate dosages for at least 6 months, but had failed to respond. Consequently, they were shifted to citalopram, titrated up to the dose of 40 mg, within 2 weeks. After 4 months of this regimen, 14 out of the total of 18 patients had shown a reduction in OC symptoms, as assessed by the decrease in the Yale-Brown Obsessive Compulsive Scale total score; no relevant side-effects were reported, except for a mild nausea in four patients within the first few days of treatment, which quickly disappeared. The use of citalopram would appear to be an useful strategy in refractory OCD cases.