Mandatory crash helmet wearing for moped (and motor cycle) riders was made mandatory in Denmark as per January 1, 1977. A rise in helmet use among moped riders from approximately 30% to about 98% followed immediately.

The present study examines the epidemiological effects of the legislation relating our findings to the existing knowledge on 7 biomechanical protective effect of helmet use. The material used in the study consists of 3,298 injured moped riders registered at Odense University Hospital during the period January 1, 1973 to December 31, 1977, thus including one year after the enactment. There was a significant reduction in the number of lesions to the head among helmet users. The proportion of victims aquiring significant cerebral lesions seemed to have declined over the years prior to the enactment, concomitant with a slow but steady increase in helmet use. It is tentatively concluded, that the voluntary increase in helmet use obtained over the period 1973 to 1976 actually reached the groups most likely to get involved in accidents leading to severe cerebral lesions. No cases of helmet-induced lesions to the neck and throat were found in the population studied.