Breastmilk is considered an optimal food for infant development especially during the first 6 months of life. However, little evidence exists regarding maternal dietary intake and infant growth. We evaluated how adherence to the DASH diet in lactating women is associated with the infant weight, height and head circumference at birth, 2 and 4 months of age. A cross-sectional study. The present study was conducted with 292 lactating mothers and their infants. A validated and reliable 168-item food frequency questionnaire (FFQ) was used to assess mothers' dietary intakes. To evaluate adherence to the DASH diet among lactating mothers, we scored food items based on the Fung method. Lactating mothers in the highest tertile of adherence to the DASH diet consumed significantly lower amounts of fat, cholesterol, salt, red and process meats and higher amounts of vitamin C, B1, B9, whole grains, low-fat dairy, fruits, vegetables and dietary fiber compared to lactating mothers in the lowest tertile (P < 0.05). No significant association was found between mothers' adherence to the DASH dietary pattern and any of the infant growth indices (P > 0.05). Lactating mothers' adherence to the DASH diet was not associated with growth indices among exclusively breastfed infants.