The objective of this study was to evaluate the frequency and consequences of the presence of residual symptoms in patients treated for major depression. The literature specifically focused on recovery and residual symptomatology of depression was reviewed. Thirty per cent or more of treated patients present residual symptoms. These symptoms appear to be associated with a higher frequency and larger number of relapses and equally affect the outcome of depression in different age groups. They also seem to have a major impact on work and psychosocial functioning because of cognitive dysfunction and a reduction in social interaction affecting patients' quality of life. We found that there is scant literature on residual symptoms contrasting with the profuse reports on single or multiple antidepressant drug trials. Studies focusing on this important issue in the treatment of depression are needed.