Although cancer mortality in young adults accounts for only a small proportion of all cancer deaths, it is important since it provides useful indications of the most likely future trends, and relevant information on the role of exposure to specific, or newer, carcinogens. We, therefore, analysed trends in cancer mortality between 1955 and 1985 among Italian men and women aged 20-44 years. In those three decades, overall cancer mortality declined steadily, by 27% in young women (from 33.8 to 24.7/100,000, world standard) but only by 3% (from 27.3 to 26.4/100,000) among men. The decline for men, however, was 16% from the peak rate of 31.5 reached in 1970-1974. The major underlying component causing the different trends in the two sexes was lung and other tobacco-related neoplasms, which had been considerably on the increase in young men up to the early 1970s, and levelled-off thereafter, while showing no appreciable change in women. The falls were about 50% for stomach cancer in both sexes, and over 80% for cervical cancer. A clear impact of improved treatment was reflected in the substantial declines in Hodgkin's disease, of testicular cancer in the last decade and, possibly, in the favourable trends in cancers of the breast, bone, brain and leukemias over the most recent calendar periods. Only two sites showed appreciable and persisting upward trends: oral cavity in men and skin melanoma in both sexes. They therefore constitute priorities for intervention in the near future.