Currently, 17 states mandate the daytime use of motorcycle headlights. The purpose of these laws is to make the motorcyclists more conspicuous and reduce the number of daytime multi-vehicle collisions. The effectiveness of the laws is examined by comparing the proportion of daytime fatal, front, and side-angle collisions between states with and without such laws. The comparison is based on all motorcycle fatalities recorded by NHTSA for the years 1975-80. The analysis shows no statistically significant difference between states with and without such laws, suggesting that daytime headlight laws are ineffective. Several explanations of this negative finding are explored.