Employing the vital statistics from January 1, 1979 to December 31, 1994 in Hokkaido Prefecture, Japan, we investigated the relationship between suicide (ICD 9 code, El15) and days of the week. In one day 1.97 males and 0.98 females committed suicide on average. On Saturdays the number of suicides per day was the smallest. On Mondays it was the highest. When the days were classified into (1) a holiday, (2) the day before a holiday, (3) the day after a holiday (4) the day both before and after a holiday and (5) others, the rate of suicide was the lowest in the days before a holiday. In the days after a holiday, however, the rate was the highest. The same tendency was also noted when the subjects were classified into several subgroups from the viewpoint of ages, seasons or calendar years. The time relation of holidays seemed to have something to do with the intention to commit suicide.