During the past decade, treatment options for depression have increased with the introduction of new agents. Older agents, such as tricyclic antidepressants and monoamine oxidase inhibitors, increase noradrenergic and serotonergic neurotransmission. Attempts to separate antidepressant effects from adverse effects led to the development of selective serotonin reuptake inhibitors (SSRIs). Citalopram is the newest SSRI to be marketed in the United States. Of all SSRIs on the market, it is the most selective for serotonin reuptake pump. Its efficacy in treating depression was evident in both placebo-controlled and comparator trials. In addition, citalopram was studied in the treatment of other psychiatric disorders. The agent has less inhibition of cytochrome P450 enzymes than other SSRIs, possibly giving it a lower potential for drug interactions.