OBJECTIVE The effects of low maternal hemoglobin levels on the immunological and nutritional components of breast milk at different maturation stages were investigated. METHODS Colostrum, transitional and mature milk were collected from 25 mothers with normal hemoglobin levels (control group) and 18 mothers with hemoglobin levels below 11 g/dL (anemia group). Total protein, antibodies, complement proteins, fat and calorie, lipase, iron, transferrin levels, total iron-binding capacity, latent iron-binding capacity (LIBC) and transferrin saturation index (TSI) were determined. RESULTS In contrast to the control group, anemic mothers had higher total protein levels in milk, lower IgA and IgG levels in colostrum, lower C3 protein levels in milk, lower C4 protein levels in colostrum and transitional milk, higher fat in the colostrum and lower calorie content in mature milk. In both groups, lipase was lower in mature milk and iron concentration was similar. Transitional and mature milk from anemic mothers had higher LIBC and lower TSI values. CONCLUSION A decrease in maternal hemoglobin levels causes immunological and nutritional alterations in milk at different maturation stages. Special measures must therefore be taken for mothers at risk of developing anemia to ensure they can provide high-quality milk to their babies.