The current study provides estimated rates of suicide among users of antidepressant drugs. The data were derived from two population-based data resources: United Kingdom general practitioners using computers provided by Value Added Medical Products, Ltd., and Group Health Cooperative of Puget Sound. The results apply specifically to these populations. The overall rates of suicide in ever users of the study drugs usually used to treat depression were 6.5 X 10-4 person-years in persons present in the U.K. resource and 5.1 X 10-4 person-years in members of The Puget Sound group. Rates of suicide among users of particular antidepressant drugs varied somewhat, but the rates were consistent with biologic variability, with the possible exception of rates for mianserin (based on 4 exposed cases), which were higher than rates for other antidepressants. Consistent findings were (1) suicide rates are substantially higher in men than in women, and (2) the use of firearms as a mode of suicide is common in the northwest United States and uncommon in the United Kingdom.