Background: Injuries caused by both non-use of and substandard helmets in motorcycle accidents place a substantial cost on both the Vietnamese government and on victims and their families who are unfortunate enough to experience such an event. Objective: To estimate Vietnamese households' willingness to pay (WTP) for a standard motorcycle helmet and to determine factors that affect the households' decision regarding the price at which they would purchase a motorcycle helmet. Method: A contingent valuation survey was administered to 420 households in two urban districts and one suburban district of Hanoi from January 2007 to February 2007. Both discrete-choice format and open-ended questions were used to examine households' WTP for a motorcycle helmet. Descriptive analysis and multivariate analysis were used to estimate possible predictors of households' WTP. Result: A total of 414 households agreed to participate in the study, giving a response rate of 98%. Eighty-seven percent of respondents owned a motorcycle helmet. Sixty-two percent of respondents agreed to purchase a helmet at the market price of Vietnamese Dong (VND)150 000 ($US9.38) [year 2007 values]. Households' WTP varied from VND81 635 to VND289 674 ($US5.1-18.1), with a mean of VND163 794 ($US10.24) and a median of VND161 718 ($US10.11). It was estimated that if the government subsidizes VND61 043 ($US3.82) for a helmet, 99% of the study population are willing to pay the additional cost for a standard helmet. Those households with a higher income and where the respondents were aged 40-55 years were more likely to purchase a helmet than those with a lower income and those of other ages. Conclusion: Respondents were prepared to pay a higher price than the market price of a standard helmet. To improve the quality of helmets in Vietnam, it is recommended that the government subsidize a helmet programme in conjunction with other programmes (such as education and strict enforcement policies) in order to increase the ownership of quality helmets in Vietnam and thereby reduce the severity of motorcycle road traffic injuries.