The decomposition of leaf litter of four selected dominant tree species, Vatica lanceaefolia, Artocarpus chaplasha, Lagerstroemia speciosa and Magnolia hookeri was studied during July 2011-June 2012 in a semievergreen forest of Assam, North East India. The weight loss pattern and concentration of N, P and K were evaluated. The annual decomposition constant (k) ranged from 3.23 to 7.8 year -1 and was positively correlated with rainfall, soil temperature, soil moisture content and total N. Litter quality and initial chemistry affected the rate of decomposition. L. speciosa having highest initial N, decomposed at a relatively faster rate. Rapid weight loss was observed during the monsoon period. The present findings indicate that rapid nutrient cycling is enhanced by fairly high decay rates of the dominant tree species maintaining proper nutrient cycling in this tropical semi-evergreen forest ecosystem.