Data from the First and Second Malaysian Family Life Surveys, fielded in 1976 and 1988 respectively, are analyzed to examine long-term trends in breastfeeding in Peninsular Malaysia, educational and ethnic differences therein, and the quality of retrospective data on infant feeding. There was a steady decrease between the mid-1950s and mid-1970s in the percentage of babies who were ever breastfed, but there has been a nearly monotonic increase since 1975. Part of the observed change in overall breastfeeding rates is attributable to the changing composition of the Malaysian population. Over time, the percentages of births to population subgroups with higher rates of breastfeeding--particularly Malays and more highly educated women--have increased. However, there is also evidence of changes in women's rates of breastfeeding within these subgroups. Many Malaysian infants have a duration of total breastfeeding (including with supplementation) that is considerably shorter than WHO's recommended duration of exclusive (unsupplemented) breastfeeding (4 months). Moreover, nearly all Malaysian infants who are breastfed are first given supplementary food or beverage shortly after birth. Breastfeeding promotion efforts in Malaysia need to give more emphasis to the appropriate timing and types of supplementary feeding.