Although homicidal tendencies are well recognized in the depressive psychoses, this medico-legal aspect of the illness receives only cursory mention in text-books, e.g. Henderson and Gillespie and Noyes, if it is referred to at all. Inasmuch as it is on this most serious complication that the psychiatrist is most liable to be asked to give evidence in court, there would seem to be good reason for examining the factors leading to such behaviour, and comparing them with similar data from non-depressive homicides. It is hoped that these notes will show a behaviour complex peculiar to the melancholic subjects.