To critically review the antiobsessional properties of serotonin-norepinephrine reuptake inhibitors (SNRIs) (venlafaxine and clomipramine) in the treatment of obsessive-compulsive disorder (OCD) as an alternative to selective serotonin reuptake inhibitors (SSRIs), which are currently considered the first-line treatment of OCD. A MEDLINE search was performed to identify clinical trials with the SNRIs venlafaxine and clomipramine published from 1996 to 2004 (keywords: SNRIs, venlafaxine, duloxetine, and clomipramine, each matched individually with the term OCD), focusing on the best-designed studies for inclusion. Much of the literature about SNRIs in OCD supports the efficacy of these compounds in the treatment of OCD. However, double-blind, placebo-controlled studies with venlafaxine are lacking, and the most relevant studies consist of active comparison trials between SNRIs and SSRIs. In these studies, SNRIs seem to be as effective as SSRIs in OCD; SNRIs might be preferred for patients with certain types of treatment-resistant OCD or those with particular comorbid conditions. A large number of placebo-controlled and active comparison trials with clomipramine document efficacy in OCD, and meta-analytic studies suggest a small superiority over SSRIs. Compared with clomipramine, the SNRI venlafaxine showed fewer side effects and better tolerability. The SNRIs may represent a valid alternative to the SSRIs, particularly in specific cases. Double-blind, placebo-controlled studies are, however, needed to confirm the positive findings reported by several studies with venlafaxine.