BACKGROUND: Home fortification using sachets of micronutrient powder (e.g. "Sprinkles") is a food-based approach offering an alternative to high dose vitamin A (VA) supplements for infants. The primary objective was to investigate the impact of VA-home fortification on infant VA pool size. The secondary objective was to compare VA status of infants assessed by the modified relative dose response (MRDR) test before and the (13)C-retinol isotope dilution ((13)C-RID) test in the same infants after vitamin A supplementation. METHODS: A randomized-controlled trial was conducted in 7-9 month old infants in Ghana. Eligible children were randomly allocated to receive a daily sachet of "Sprinkles" with or without VA for 5 months added to complementary foods. The MRDR test indirectly determined VA liver reserves at baseline and the (13)C-RID determined VA body pool at follow-up in the same cohort of children. RESULTS: At baseline, the MRDR values (95 % CI) for infants were comparable in the intervention and control groups: normal at 0·032 (SD 0·018) (0·025-0·038) and 0·031 (SD 0·018) (0·024-0·038), respectively. After intervention, total body stores (TBS) and liver retinol concentrations did not differ between intervention and control groups; TBS were 436 (SD 303) and 434 (SD 186) μmol, respectively, and estimated liver concentrations were 0·82 (SD 0·53) and 0·79 (SD 0·36) μmol/g liver, indicating adequate reserves in all children. CONCLUSIONS: Both the MRDR and (3)C-RID tests confirmed that the infants had adequate VA status before and after home fortification of their complementary foods. These tests offered more information than serum retinol concentrations alone, which predicted VA deficiency using current suggested cutoffs not corrected for inflammation status.