his retrospective study examined duration of breast-feeding and concurrent contraceptive use among 5,648 Peruvian women. Data were gathered during 1986-1992 as part of the Demographic and Health Survey (DHS). The women gave birth to 7,951 infants, 95% of whom were breastfed; 44% of the mothers used contraception while breastfeeding. Consistent with the literature, mothers using oral contraception breastfed for significantly less time than those using other methods. Unexpectedly, mothers using periodic abstinence or withdrawal breastfed longer (15.5 and 15.3 months) than those using other methods or non-contraceptors. Among mothers changing contraceptive methods while breastfeeding the same child, those changing to abstinence and withdrawal breastfed longest (18 months). The relationship of duration of breast-feeding with contraceptive use remained after controlling for other predictors of duration of breast-feeding. Additional data are needed to explain this phenomenon in Peru and perhaps elsewhere.