Interest in the monoamine oxidase (MAO) inhibitors has been revived over the past fifteen years since the publication of studies and reviews which argue their relative safety and efficacy in certain patient subgroups. The authors conclude that there is a continuing role for the MAO inhibitors in treating atypical depressive illness and panic disorders. Careful selection of patients to be commenced on MAO inhibitor treatment is advised. When prescribed alone or in combination with lithium there is evidence to support a usefulness for MAO inhibitors in depression resistant to the tricyclic antidepressants. Their efficacy in the depressed phase of bipolar affective disorder or in combination with the tricyclic antidepressants remains unproven. The risk of anaesthesia while a patient is receiving MAO inhibitor treatment may be less than heretofore believed. There is realistic hope of finding among the short-acting selective MAO inhibitors an effective antidepressant which is also free from tyramine related effects. With the increasing difficulties of evaluating new drugs on account of ethical and governmental constraints, it may however be some time before the preliminary hopeful findings can be substantiated in larger groups of patients.