In this study concerning the whole of Belgium, the trends in infant mortality and of its two main components, neonatal mortality (NNM) and post-neonatal mortality (PNNM) from 1960 to 1981 were studied. NNM and PNNM followed similar trends until 1975 when PNNM became steady at a rate of 4-4.5%. On the other hand, an acceleration was observed in the rate of decrease for NNM, from -52% before 1975 to -71% between 1975-1981.