Background Mandatory motorcycle helmet use regulation is essential, but its enforcement is even more important for head injury prevention, especially in a country like Nepal with a high share of motorcycle traffic. We assessed the impact of one-sided motorcycle helmet use regulation in Nepal, where helmet use is mandatory, but only drivers are fined for not using a helmet, while passengers do not get punished.

Methods In a combined observational and questionnaire survey, knowledge about the helmet use regulation was assessed and adherence to the law evaluated. Data was collected at seven sites throughout the country, including rural and urban regions.

Results The observation of 2548 motorcycle riders reveals a dichotomy of motorcycle helmet use in Nepal. While 98% of drivers used a helmet, only less than 1% of observed passengers used a helmet. The questionnaire survey of 220 riders reveals a lack of knowledge about the existing mandatory helmet use for passengers, most probably due to inadequate enforcement of the helmet rule for them. The survey further reveals that helmets would be readily available for passengers, as over 50% have access to a helmet.

Conclusion In Nepal, the helmet use of motorcycle passengers is critically low. The sole existence of rules for mandatory helmet use is not enough, regulatory changes in the traffic-fine structure are necessary to increase helmet use and prevention of consequences of head injuries.

Learning Outcomes Educating motorcycle passengers about existing rules and benefits of using a standard helmet may support motorcycle safety in Nepal.