Bicycle helmet wearing globally has increased over the past 30 years via promotion and in some cases legislation. Various reports have assessed the changes in wearing rates, accidents, injuries and cycling activity levels. A limited number of reports have analysed overall changes in accident risk per kilometres cycled, per hours cycled or in relationship to cycling levels via survey information. A significant number of findings suggest a higher accident/injury rate may result from helmet usage. Accident data from Australia, the United States, Canada, the United Kingdom and New Zealand indicate the accident rate per hour cycled or per miles cycled has increased with greater helmet usage, most likely from a greater proportion and number of upper limb injuries. Consideration is given to why the accident rate may change and if overall safety is improved or reduced by helmet usage.