A study is reported of the effect of sex, age, cubic capacity, and training on the rate of reported injury accidents in a cohort of 304 first time learner motorcycle riders resident in the Lothian and Borders of Scotland in 1983. Motorcycle in this paper includes all types of registerable two wheeled motor vehicle. Injury accidents as reported by the police were observed in this cohort over an average period of one year. The overall reported injury accident rate within the cohort was 8.2 per hundred riders. This rate does not seem to be markedly different to the Scottish rate for all riders. It was found that the cubic capacity of the motorcycle was the single most important risk factor of the four studied. The risk was disproportionately high in the 200+ cc category. Lower reported injury accident rates were observed for females and trained riders but these differences did not reach statistical significance mainly due to the low numbers of these two categories within the cohort. Contrary to popular assumption, younger riders within this cohort did not have higher injury accidents. A large proportion of the riders who had been involved in injury accidents within the cohort and who had registered 50 cc motorcycles were found to be riding higher capacity (mainly 200+ cc) motorcycles at the time of accident. There was a very low uptake of motorcycle training (7.3%) by the cohort. Approximately 15% of the cohort was female, a higher percentage than those reported by other studies.