On July 1, 1981 the Italian government received and implemented an E.E.C. directive dated 1978 calling for the reduction of lead in fuels from 0.6 to 0.4 g/L. The effectiveness of this legislative measure is evaluated here by comparison of data on atmospheric lead levels in the city of Turin, and blood lead levels in A.V.I.S. (Italian Association of Blood Donors) donors in Turin and the countryside (control group), before (1977) and after (1986, 1987) the enforcement of the law. The results show that the implementation of the law has contributed to a decrease in the atmospheric lead levels. The analysis of blood lead concentration revealed an evident biological response to this environmental change: there was a decrease in blood lead level between 1977 and 1987, in both the countryside (control group) and, to a lesser extent, in the city.