The combined serotonin-norepinephrine reuptake inhibitor, venlafaxine XR, has demonstrated significant response and remission in patients diagnosed with depression when measured with the Hamilton Depression Rating Scale (HAM-D). This pooled analysis of data from five studies compared the sustained remission of depressive symptoms in patients treated with venlafaxine XR, the selective serotonin reuptake inhibitors (SSRIs) fluoxetine or paroxetine, or placebo. Data from 1391 subjects enrolled in five active and placebo-controlled studies who met the DSM-III-R or DSM-IV criteria for major depressive disorder were analysed. Three treatment groups were compared: venlafaxine XR (n = 560), fluoxetine/paroxetine (n = 298) and placebo (n = 496). Mean treatment duration was 8 weeks. Responders were defined as those patients whose HAM-D-21 score decreased by > or = 50% from baseline. Remission was defined as a HAM-D-17 score < or = 7. Sustained remission was defined as maintenance of remission through week 8 or the end of treatment (if before week 8) and for > or = 2 weeks. Between-group rate comparisons in outcome measures were carried out using Fisher's exact and log-rank tests. Venlafaxine XR produced significantly higher rates of sustained remission in depressed patients compared to fluoxetine/paroxetine or placebo over this 8-week treatment period. As early as week 2, a significantly greater proportion of patients treated with venlafaxine achieved improved depression scores (remission and response). A significantly greater rate of remission and sustained remission occurred with venlafaxine compared to placebo. Remission was achieved earlier with venlafaxine and lasted throughout the remainder of the study. These results demonstrate that venlafaxine XR is more effective than fluoxetine/paroxetine for sustaining remission of depressive symptoms.