Seven drugs of the imino-dibenzyl group are now generally available in Great Britain (imipramine, amitriptyline, desipramine, nortriptyline, protriptyline, trimipramine and opipramol). All are similar in their actions and side-effects. Imipramine, the first to appear, has been shown to be more effective than placebo in the treatment of depression, though with much better results in men than in women (M.R.C. Clinical Trial, 1965). Desipramine, a metabolite of impramine, was introduced with the claim that its action was quicker than that of imipramine, though this has never been clearly demonstrated. Trials of desipramine against imipramine (Waldron and Bates, 1965; Rose and Westhead, 1964) showed no significant difference between these drugs. Comparison of amitriptyline and imipramine (Burt, Gordon, Holt and Hordern, 1962), showed amitriptyline to be at least as effective as imipramine and significantly superior in the treatment of endogenous depression. Comparisons of nortriptyline and amitriptyline (Forrest, Affleck, Gibb and Priest, 1964; Rose, Leahy, Martin and Westhead, 1965) showed no significant difference between these drugs.