Since the inception of cancer registration in Singapore in 1968, the incidence rates of malignancies have been monitored among the 3 major ethnic groups--Chinese (77% of population), Malays (15%) and Indians (6%). Substantial changes in incidence at various sites were observed in the period 1968-1982, which seem to represent a shift from the pattern of cancer incidence in China towards that prevailing in the West. We now report on the Singapore Chinese experience, in which the following changes were notable: decreases in rates of cancers of the stomach and oesophagus and increases in rates of cancers of the lung, colon, rectum, skin (excluding melanoma), breast and ovary. For several sites, the secular changes differed among age groups; among women under 50 years of age breast cancer increased particularly sharply and lung cancer decreased. Environmental and personal factors, potentially responsible for the change, are discussed.