OBJECTIVE: This study compared deaths from traffic accidents on Friday the 13th with those on other Fridays in a national population. METHOD: The author examined the daily deaths from traffic accidents by sex and age and the mean daily temperature in Finland, 1971–1997. Adjusted risk ratios for death on Friday the 13th versus other Fridays were obtained by negative binomial regression. RESULTS: In men, the adjusted risk ratio for dying on Friday the 13th, compared with other Fridays, was 1.02, but for women, it was 1.63. An estimated 38% of traffic deaths involving women on this day were attributable to Friday the 13th itself. CONCLUSIONS: Friday the 13th may be a dangerous day for women, largely because of anxiety from superstition. The risk of traffic deaths on this date could be reduced by one-third, although the absolute gain would remain very small: only one death per 5 million person-days.