BACKGROUND: A rare but reversible cause of dilated cardiomyopathy occurs in infants born to vitamin D deficient mothers due to hypocalcaemia.CASE REPORT: We report a case of dilated cardiomyopathy due to hypocalcaemia secondary to maternal vitamin D deficiency in an infant presented with seizure disorder and heart failure. This was a four-month old female infant with respiratory distress and acute heart failure. The  cause of her cardiac failure was dilated cardiomyopathy. Concomitant community acquired pneumonia was diagnosed on chest X ray. Despite treatment, the infant's clinical condition worsened. The mother was found to be house-bound, dark skinned and veiled while going outside of home. Laboratory studies revealed hypomagnesaemia and hypocalcaemia. The vitamin D levels of both the infant and the mother were found to be low. The infant was treated for the deficiency state until her cardiac condition fully recovered.CONCLUSION: This case report demonstrated the direct relationship between maternal vitamin D deficiency and the infant’s acute heart failure. It also highlighted the importance of vitamin D supplementation during pregnancy in order to prevent the cardiac complication of maternal vitamin D deficiency in the infants.KEYWORDS: Dilated cardiomyopathy, Hypocalcaemia, vitamin D, cardiac failure