Fluvoxamine is the selective serotonin re-uptake inhibitor with the largest database in the treatment of obsessive-compulsive disorder, a severe, and often chronic, anxiety disorder associated with substantial impairment in functioning. The selective serotonin re-uptake inhibitors represent a first-line treatment in patients with obsessive-compulsive disorder. These agents work primarily by blocking the re-uptake of serotonin into the presynaptic nerve terminal, which is believed to be mediated by their effects on the serotonin transport system. In the last two decades, the anti-obsessional effect of fluvoxamine has been tested in several double-blind, placebo-controlled and active-comparison studies, demonstrating its superior efficacy over obsessions and compulsions compared with non-serotonergic antidepressants (i.e., desipramine) and equal efficacy to clomipramine (a tricyclic antidepressant with potent serotonin re-uptake inhibition) and other selective serotonin re-uptake inhibitors (paroxetine and citalopram). However, compared with clomipramine, the selective serotonin re-uptake inhibitor fluvoxamine showed fewer side effects and better tolerability. This reflects the poor affinity of this compound for adrenergic, muscarinic, cholinergic or histaminergic receptors.