This study aimed to determine the effectiveness of antipsychotic augmentation of serotonergic antidepressants in the management of treatment-resistant obsessive compulsive disorder by carrying out a meta-analysis of all randomized controlled trials. Studies selected through a literature search conducted in March 2006. Ten trials comparing antipsychotic drugs versus placebo met inclusion criteria (haloperidol [n=1], risperidone [n=3], olanzapine [n=2], quetiapine [n=4]). A total of 157 patients were randomized to study drug and 148 were randomized to placebo. Response occurred more often among patients randomized to antipsychotic drugs. The weighted combined response rate ratio by random effects meta-analysis was 3.31 (95% CI 1.40–7.84). Significant between studies heterogeneity was partly explained by the definition of refractoriness, the type and dose of the drug used and the inclusion or exclusion of patients with tic disorders. The study supports the use of antipsychotic drugs as an augmentation strategy but more and larger trials are needed.