This study was conducted to examine weight change of exclusively breast-fed infants during the first week and through the first 24 days of life, and to evaluate the effect of breast-feeding factors and maternal characteristics on early weight change in the infants. The weights of 21 infants were recorded on day 1 (day of birth), and on days 3, 7, 10, 17, and 24, and the data analysed to evaluate weight change over the period. Multiple regression analysis was used to assess whether birth weight as well as maternal and breast-feeding factors were significant predictors of weight on day 24. Nineteen of the 21 infants gained weight between days 1 and 3, and 20 infants gained weight between days 3 and 7. All infants gained weight over the 24-day period and their weights at day 7 and day 24 were significantly different (P < 0.05 and P < 0.01, respectively) from their birth weights. Multiple linear regression analysis showed that significant (P < 0.01) predictors of weight gain by day 24 included birth weight, mother's educational level, whether the baby cried before feeding, and length of feeding time periods. This is the first study of weight change in the early days and weeks of life of exclusively breast-fed newborn infants in Jamaica. The infants showed significant weight gain during the study period and weight gain was affected by certain maternal and breast-feeding factors. © 2000 Blackwell Science Ltd.