To investigate the effects of age, type of road and time of day on the risks of collision among drivers living in Metropolitan Toronto, age-specific rates of collision per million miles were calculated for each sex and several levels of demerit points, based on the records of drivers in 1978. These rates were used to generate expected frequencies of collision for the amounts of driving reported on city street, limited access roads, and other roads outside the Metropolitan boundary. City streets had increased hazard, and limited access roads had a markedly reduced hazard. Driving in rush hour was associated with a slight increase in risk and driving at night with a moderate, statistically significant, increase. For comparisons between sexes, ages or demerit point levels, the only significant difference was the increase in collisions observed after dark relative to the number expected with increasing age of the driver. This and other comparisons, although not statistically significant have implications for the training of drivers and for modification of the driving environment.