Riboflavin and vitamin B6 status of mothers from a low-income group were assessed by erythrocyte glutathione reductase activation and erythrocyte aspartate aminotransferase activation tests respectively, at different stages of lactation. Levels of these vitamins in milk were also measured. The majority of the women had biochemical evidence of vitamins B2 and B6 deficiency. There was a bizarre reduction in erythrocyte glutathione reductase activation from 6 to 30 d post partum. Levels of riboflavin in milk were in general satisfactory, but vitamin B6 levels were lower than the values reported from developed countries. Clear-cut correlations between the enzymatic indices of vitamin status evaluation and milk levels of the corresponding vitamins were not apparent.