Orthostatic hypotension, one of tricyclic antidepressant treatment's side effects, is also a factor in limiting adequate antidepressant dosing. We tested in a double-blind, crossover, placebo-controlled study the effect of low doses (4 mg/t.i.d.) of yohimbine in 12 patients with depression with clomipramine-induced orthostatic hypotension. Yohimbine, a selective alpha 2-adrenoceptor antagonist, had a favorable effect in orthostatic hypotension and induced a significant increase in blood pressure. A pharmacodynamic and pharmacokinetic interaction between yohimbine and clomipramine or demethylclomipramine was discussed.