The paper discusses the problems of wind loading of urban transit vehicles in the context of the overturning problem. It is shown that vehicles will respond to gusts of the order of only a few seconds in duration. The available aerodynamic information for vehicle shapes is reviewed, as is the nature of the wind environment in urban areas. The implications of these data are placed in a simplified probabilistic perspective that suggests that the risk of overturning can become very significant if a number of factors are unfavourable. While the details of assessing the risks more precisely are described and have been developed in detail elsewhere, they cannot be applied to this problem until better information for particular cases is developed. Better data on both vehicle aerodynamics and the wind statistics for actual vehicle routes are needed.Key words: urban transit vehicles, overturning, wind loading, aerodynamics, wind engineering.