Few previous studies have evaluated the differential benefits of breastfeeding on infantneurodevelopment depending on the level of prenatal alcohol exposure (PAE). This study aims to identify if the association between breastfeeding and infant neurodevelopment is modified by pattern of PAE. The study sample included 392 Ukrainian infants born to pregnant mothers prospectively enrolled in a cohort study who reported various levels of prenatal alcohol consumption. Infant neurodevelopment was assessed at 6- and 12-months using the Bayley Scales of Infant Development II (BSID-II) Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI). Linear regression modeling with interaction terms and stratification by PAE group was used to determine the relationship between breastfeeding and infant neurodevelopment. When controlling for PAE and key covariates, breastfeeding had a positive significant association with the PDI and MDI at 6 months but not at 12 months. The interaction terms were significant at the 0.05 level for the MDI and PDI at 6- and 12-months, indicating a joint effect of PAE and breastfeeding on infant neurodevelopment that goes beyond the effects of PAE and breastfeeding alone. Infants exposed to high levels of PAE who were breastfed had the greatest mean increase in PDI and MDI scores at both 6- and 12-months compared to infants who were never breastfed. There is a significant joint effect of PAE and breastfeeding on infant neurodevelopment at 6- and 12-months. Infants exposed to high levels of PAE may experience the greatest benefits from breastfeeding, especially for durations of four months or longer.