Since it was first reported by Kuhn in 1957, the value of imipramine in the treatment of depressive illness has become generally recognized and confirmed by clinical trials (Blair, 1960; Daneman, 1961; Rees et al., 1961). It continues to hold an important place in therapy despite the introduction of many other antidepressant drugs and the occasional adverse report (Ashby & Collins 1961). Nevertheless the indications for its use are by no means established. It has been claimed that certain types of depression respond better than others: “psychotic” better than “neurotic” (Azima, 1959), “endogenous” better than “reactive” (Ball and Kiloh, 1959). Yet the difficulty of making these categorical distinctions, and of making reliable comparisons between the findings based upon them by different workers remains notorious. It is clear, however, that only a proportion of depressed patients respond well to imipramine. It is also certain that within the group which does respond well are to be found representatives of every type and degree of depressive state. There is evident need, therefore, for information that will help to indicate which characteristics of an individual will render him more or less susceptible to imipramine, and there does not appear to have been any study particularly devoted to this. In this paper we give the results of correlating certain clinical features of depression with the response to treatment by this drug.