The renewed use of modified forms of narcosis, generally given together with ECT and antidepressant drugs, arose from a series of observations made during attempts to treat a group of chronically tense patients. These patients, the majority of whom had been diagnosed as ‘chronic tension states', had been referred to the Department of Psychological Medicine at St. Thomas' Hospital for assessment regarding their suitability for modified leucotomy. Birley (1964), in a follow-up study of previous patients with ‘tension states' treated by leucotomy at St. Thomas' Hospital, had found that many developed clear-cut attacks of depression following the operation. This suggested to one of us (W.S.) that such ‘tension states' might have been masked depressive illnesses, in whom the underlying diagnosis had been missed. Consequently it was decided that in the future such patients should be treated with suitably long courses of ECT, together with one or both groups of antidepressant drugs, before any question of recommending leucotomy arose. As a result, a considerable number of these patients were greatly improved and no longer required a leucotomy. Others, however, became more tense and distressed during treatment with ECT and drugs; modified narcosis, therefore, was given in addition, to allow the full course of ECT to be completed. It was then that another of us (C.W.) observed that patients who were treated with combined narcosis, ECT and antidepressants appeared to respond more favourably, and were much less upset by the treatment, than those receiving ECT and antidepressants alone. In a preliminary report published in 1966, Sargant, Walter and Wright described a group of 73 patients with ‘chronic tension states', of whom 67 per cent had improved markedly with further treatment of their underlying depression. It was noted that 15 of the 37 patients treated with ECT and antidepressants alone still required a leucotomy, while in the group treated with modified narcosis in addition to ECT and antidepressants the operation was needed in only 3 of the 36 patients. It appeared, therefore, that the addition of narcosis to drugs and ECT greatly improved the recovery rate.