Data from the death register, police-reported crashes, hospital admissions and a community survey were used (i) to calculate a 'best estimate' of the number of pedal cyclists injured in crashes in Western Australia and (ii) to examine some of the problems resulting from the under-reporting of bicycle crashes in police data. It was estimated that the number of pedal cyclists injured in crashes over one year in Western Australia was 38,982, of which only about 2% (868) were reported to the police and 2.4% (919) were injured severely enough to be hospitalised. Police-reported bicycle crashes were found to be very different from those recorded in hospital admissions data and cases reported in the community survey. Police-reported cases tended to be the more severely injured, they involved another vehicle more frequently, they occurred on-road, and there were relatively fewer pedal cyclists in the 5-14 years age group. The costs of injury-producing bicycle crashes were found to be $46m. using the 'best estimate', compared with $22m. using police-reported cases. About 15% of the costs of crashes involving bicycles occurred in off-road crashes. There is a need to include unreported and off-road crashes when developing and evaluating bicycle safety strategies, and when allocating road safety resources between road user types.