The efficacy of nortriptyline in the treatment of post-stroke depression was assessed by a double-blind study in thirty-four patients. Half of the patients had major depression. There was a significantly greater improvement in depression in patients treated with nortriptyline than in a similar group of placebo-treated patients. Depression was measured by the Hamilton depression scale, Zung depression scale, present state examination, and an overall depression scale. Successfully treated patients had serum nortriptyline levels in the therapeutic range. Post-stroke depressions are common, severe, and longstanding, and the demonstrated efficacy of nortriptyline provides an important addition to the treatments available for stroke patients.