['To describe breastfeeding practices and investigate the influence of exclusive breastfeeding in early infancy on the risk of infant deaths, especially those attributable to respiratory infections (ARI) and diarrhea.', 'A prospective observational study was conducted on a birth cohort of 1677 infants who were born in slum areas of Dhaka in Bangladesh and followed from birth to 12 months of age. After enrollment at birth, the infants were visited 5 more times by 12 months of age. Verbal autopsy, based on a structured questionnaire, was used to assign a cause to the 180 reported deaths. Proportional hazards regression models were used to estimate the effect of breastfeeding practices, introduced as a time-varying variable, after accounting for other variables, including birth weight. Overall neonatal, postneonatal and infant mortality, and mortality attributable to ARI and diarrhea were measured.', 'The proportion of infants who were breastfed exclusively was only 6% at enrollment, increasing to 53% at 1 month and then gradually declining to 5% at 6 months of age. Predominant breastfeeding declined from 66% at enrollment to 4% at 12 months of age. Very few infants were not breastfed, whereas the proportion of partially breastfed infants increased with age. Breastfeeding practices did not differ between low and normal birth weight infants at any age. The overall infant mortality rate was 114 deaths per 1000 live births. Compared with exclusive breastfeeding in the first few months of life, partial or no breastfeeding was associated with a 2.23-fold higher risk of infant deaths resulting from all causes and 2.40- and 3.94-fold higher risk of deaths attributable to ARI and diarrhea, respectively.'] Does exclusive breastfeeding reduce acute respiratory infection and diarrhea deaths among infants in Dhaka slums?