These practical guidelines for the biological treatment of unipolar depressive disorders in primary care settings were developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBP). They embody the results of a systematic review of all available clinical and scientific evidence pertaining to the treatment of unipolar depressive disorders and offer practical recommendations for general practitioners encountering patients with these conditions. The guidelines cover disease definition, classification, epidemiology and course of unipolar depressive disorders, and the principles of management in the acute, continuation and maintenance phase. They deal primarily with biological treatment (including antidepressants, other psychopharmacological and hormonal medications, electroconvulsive therapy, light therapy).