Trends in death certification rates from all motor vehicle accidents and motor-cycle accidents in Italy over the period 1955-79 were analysed. For both sexes, age-standardised mortality rates per 100,000 population increased steadily up to the early 1970's, reaching 40.08/100,000 males in 1972 and 11.05/100,000 females in 1973. Marked downward trends followed, and the 1977-79 rates were comparable with 1955 for males (around 28/100,000), though the total number of motor vehicles increased almost six-fold (and the number of cars over 14-fold). When age-specific rates were considered, the largest increases between the late 1950's and the early 1970's were for younger (under 25) and older (55 and over) males and younger (under 35) females. The decreases from 1974 onwards applied to both sexes and all age groups. Motor-cycle death rates increased in males up to the mid 1960's, mostly in younger (15-25) and older (over 55) age groups. A sudden, marked inversion of trends followed, starting from the younger age groups and spreading to all age groups in the mid 1970's. This pattern corresponds roughly to a 50% decrease in male death certification rates per registered motor-cycle. In absolute terms, the decline in the second half of the 1970's corresponds to about 4,000 fewer deaths per year. This is one of the major changes observed in mortality from any cause during the 1970's in Italy. Provisional data for the period 1980-82 suggest that further downward trends, albeit moderate, have continued.