The clinical characteristics and treatment outcome of a series of 107 patients referred to a mood disorders unit with an episode of "treatment resistant" Major Depression are reviewed. Subjects were categorised by diagnosis (into melancholic and non-melancholic subtypes) and by adequacy of previous treatment. At subsequent review (mean period of 37.5 months) these patients were re-assessed both in terms of outcome and which treatments had been considered to be most effective. Forty one percent of the patient group were fully recovered and a further 43% were partially improved. Different treatments were considered effective for melancholic and non-melancholic sub-types.