Is it possible to substantially reduce the incidence of injuries related to cycling through the provision of information on helmet wearing? This issue has been investigated in Skaraborg County, Sweden, where 90 percent of all pre-school children now use bicycle helmets. For children under 15, there was an average annual decrease in all bicycle-related injuries of 3.1 percent, equivalent to a decrease of 48 percent over the study period, 1978-93 (for head injuries, 59%). Sweden as a whole showed a reduction of 32 percent in bicycle-related injuries (head injuries, 43%). In Skaraborg, children have been the target of helmet-wearing programs at local and regional levels since 1982, and at national level since 1987. The elderly have not been targeted in helmet-wearing programs; currently, they scarcely wear helmets at all, and showed a significant increase in their injury rate over the period (4.7% annually). The number of concussions sustained by helmet-wearers is estimated to be one-third fewer than that of non-wearers. Comparisons with Australia and some parts of the U.S.A. indicate that, despite the significant decrease in Skaraborg, greater effects might be achievable if information is supplemented by compulsory-helmet-wearing legislation.