Incidence data pertaining to more than 250,000 cancer cases diagnosed during the years 1972-1989 among residents of urban Shanghai, China, were analyzed to determine the relative importance of the various malignancies and to discover changes over time. In the most recent 3-year period, lung cancer was the most frequent cancer among men (57.0 per 100,000 person-years, age-adjusted world standard), followed by cancers of the stomach (50.1), liver (29.6), esophagus (13.3), colon (11.2) and rectum (9.4). Among women, breast cancer leads (25.1), followed by cancers of the stomach (23.2), lung (18.8), liver (10.9), colon (10.2) and rectum (7.3). The most impressive increases in incidence rates from 1972-74 to 1987-89 were observed for cancers of the gallbladder (119% and 101% among men and women, respectively), colon (85% and 78%), and brain and other nervous system (71% and 60%). In addition, increases of 20-50% occurred for cancers of the pancreas, male lung, female breast, corpus uteri, kidney, and for non-Hodgkin's lymphoma. Rates declined notably for cancers of the esophagus (-54% and -53%), cervix uteri (-86%), and to a lesser extent (10-20%) cancers of the male stomach and liver. These observed trends can be explained only partly by improvements in cancer diagnosis and completeness of the cancer registry, and most likely reflect changes in the prevalence of risk factors in this population.