Motorcycle fatalities are increasing at an alarming rate in many South-East Asian countries, including Cambodia. Through brief face-to-face roadside interviews in Phnom Penh and four other Cambodian provinces, this article assesses Cambodian motorcyclists' attitudes, behaviours and beliefs related to motorcycle helmets. Out of 1016 motorcyclists interviewed, 50% were drivers, 40% were older passengers and 10% were child passengers. More drivers (50%) reported consistently wearing helmets, compared with older passengers (14%). Saving their life in the event of a crash was the impetus for drivers and older passengers to wear a helmet (96% and 98%, respectively). The top barriers to helmet use were: (1) 'depends on where I drive,' (2) 'I forget' and (3) 'inconvenient' or 'uncomfortable'. These descriptive findings were instrumental in shaping the Cambodian Helmet Vaccine Initiative passenger campaign to reduce the motorcycle-related injuries and fatalities to support the United Nations Decade of Action for Road Safety.