Acacia mangium is a fast-growing tree species of the family Leguminosae. In the Forest Research Institute campus, Chittagong, 80 seedlings were planted in 1979. At the age of 4 and half years the trees attained an average height of 10.3 m with 10.4 cm diameter at breast height. The growth rate is comparable to that of Eucalyptus camaldulensis and better then that of Pinus caribaea and Swietenia macrophylla which were planted simultaneously. The species, therefore, shows great promise for afforfestation in Bangladesh and further trial plantations may be raised to study its growth and performance in this country and elsewhere and for raising seed-stands and ultimately Seed-Orchards as a source of seed supply for further plantation programmes.