At the Aga Khan Hospital (AKUH), 65 infants presented with hypocalcaemic seizures, subsequently found to have rickets. Forty-six infants less than 6 months were totally or predominantly breast fed. In a subgroup of 15 mothers and their infants, we found very low plasma levels of 25(OH) vitamin D of < 5 micrograms/l and 7.5 +/- 3.3 micrograms/l, respectively. Neither mothers nor infants received vitamin D supplementation. Maternal vitamin D deficiency and non-supplementation in the infants were the likely causes of rickets in our patients. Prophylactic vitamin D 400 i.u. administered to infants up to 2 years and 800 i.u. to women in pregnancy and during lactation is recommended to prevent vitamin D deficiency.