Compulsory blood estimation of the alcohol level (B.A.L.) in road crash casualties attending hospitals was introduced in Victoria in 1974 and today enjoys widespread acceptance.At present about 19,000 samples per annum are taken in 160 hospitals and tested in a central forensic laboratory. Some 60 - 70% of driver casualties with an illegal B.A.L. are prosecuted with a successful conviction rate of 85%.Compulsory blood tests are part of a comprehensive alcohol countermeasures package which, during its operation, has seen a fall in the number of alcohol involved crashes from 50% to 38%.Since 1974 there has been a fall in the incidence of driver casualties with positive B.A.L. from 25.6% to 16% in 1985 and a fall in illegal B.A.L. from 20.1% to 13% in the same period.Male driver casualties with illegal B.A.L. outnumber female casualties 3 to 1. Blood tests have indicated the over-representation of young driver casualties and the days of the week and time of day where the percentage of driver casualties with an illegal B.A.L. is highest.