Using Irish suicide data for the period 1990?1998, the independent effects of month and day adjusting for age, gender, and calendar year effects and distinguishing between holiday and working Mondays were assessed. The male suicide rate was significantly higher on working Mondays (+31%) and Saturdays (+14%), and during April, June, and August (+17%), after adjustment for the other variables. In contrast, female suicide rates were higher only in August (+35%) and exhibited no day effect. Teenage men had a greater elevation of risk on Saturdays, Sundays, and both working and holiday Mondays than any other group. The study findings should be taken into account in the planning of specialized health care services and helplines for suicidal people. Furthermore, the findings provide support for Gabennesch's (1988) broken promise theory and the relationship between dysfunctions of the serotonergic system and suicidal behavior.