Reviews & presents studies on chronological variations in suicide rates, especially in Nordic countries. In the studies presented, there were fewer suicides in February, & more in May, June or August; the suicide rate was highest at the beginning of each month; & there were usually fewer suicides on Tuesdays & more on Wednesdays. No explanation for these variations was clearly indicated; those considered include economics, mental health, weather, birthdays & alcohol use. (RM) (69 refs.)