The aim of this study was to document the introduction rates of complementary foods to infants in the Han, Uygur and other ethnic groups living in the Xinjiang Uygur Autonomous Region, PR China. A longitudinal study of infant feeding practices was undertaken using a random sample that included all of the ethnic groups in the region. Mothers were randomly recruited and interviewed in hospitals and maternal and child health institutes in the region. A total of 1219 mothers (578 Han, 360 Uygur and 281 from "other minority" groups), who delivered babies during 2003 and 2004, were recruited. After discharge they were contacted at approximately monthly intervals during the first six months of their infant's life to obtain details of feeding practices. The overall introduction rates of water, cow's milk and solid food in Xinjiang were, respectively, 23%, 2% and 6% before discharge and 76%, 39% and 78% at six months. The rates were different between ethnic groups. Uygur mothers were most likely to feed water to their babies, with introduction rates of 57% before discharge and 95% at six months, while the corresponding rates were 6% and 77% for Han and 12% and 52% for other minority groups. Mothers from Uygur and other minorities introduced cow's milk earlier than Han mothers. Uygur mothers also introduce solid foods earlier (10% pre discharge and 91% by six months) when compared to Han (3% pre discharge and 85% by six months) and other minorities (4% pre discharge and 48% by six months). The pattern of introduction of complementary foods in this region does not follow internationally recognized practices, suggesting the need for further education of health professionals and parents.