I am a cyclist and a motorist. I fasten my seatbelt when I drive and wear a helmet on my bike to reduce the risk of injury. I am convinced that these are prudent safety measures. I have persuaded many friends to wear helmets on the grounds that transplant surgeons call those without helmets, "donors on wheels". But a book on ‘Risk' by my colleague John Adams has made me re-examine my deeply held conviction,convictions,minds,obsessions. Adams has completely underestimated,understood,underwent,underminedmy confidence in these apparently sensible precautions. What he has persuasively argued, particularly in relation to seat belts, is that the evidence that they do what they are supposed to do is very suspect. This is because of,in spite of,in contrast with,in terms ofnumerous claims that seat belts save many thousands of lives every year. There is remarkable data on the years 1970 and 1978 in which countries where seat belts are recommended,approved,accepted,compulsoryhave had on average about 5 per cent more road accident deaths following the introduction of the law. In the UK, road deaths have decreased steadily from about 7,000 a year in 1972 to just over 4,000 in 1989. There is no evidence in the trend for any effect of the seat belt law that was introduced in 1983. Moreover, there is evidence that the number of cyclists and pedestrians killed actually increased by about 10 per cent.