Marsilid has proven to our satisfaction that it is the most effective chemical to appear so far for the treatment of ambulatory depressions. Its action is physiological. We do not know its effectiveness for patients severely depressed enough to require hospitalization. Several of our patients did not require ECT, which we would otherwise have prescribed. The drug is apparently toxic to a dangerous degree to certain individuals, and toxic to very mild degrees in others. Perhaps it is a safe drug to use for a limited period. It is unclear whether total dosage, duration of treatment, or purely idiosyncracity are related to these hepatitis reactions. This is an important therapeutic advance which should be pursued further, but a safe regimen needs to be worked out as more data are accumulated.