Uttar Pradesh and Madhya Pradesh have the highest infant mortality rate both in NFHS-3 (2005–06) and NFHS-4 (2015–16); but there has been a noticeable decline in IMRs in both the states during 2005–06 and 2015–16. The study endeavours to explore the factors that explain the decline in infant mortality in these two states. Findings from multiple regression and decomposition analysis attribute low birth weight, age of the mother at birth, mother’s educational attainment, mother’s use of cooking fuel and wealth status as the major contributing factors for the decline in infant mortality between NFHS-3 and NFHS-4.