Genetic improvement of Acacia mangium for high quality sawn timber production is necessary to increase benefit of plantations and economic development. It is essential to understand genetic control of important traits for an improvement strategy of A. mangium. The study was conducted using 151 trees of 42 randomly selected families from 6 provenances in a 11 years thinned progeny trial at Ba Vi, Ha Noi. Results of the study. showed that significant difference between provenances in wood basic density but nonsigificant in modulus of elasticity (MOE) , modulus of rupture (MOR) and shrinkage. Significant differences between families were found in wood basic density, MOE, MOR, tangential and radial shrinkage, but not in longitudinal shrinkage and tangential/radial (T/R) ratio. Within provenance narrow sense heritability was moderate to high for wood basic density, MOE, MOR, tangential and radial shrinkage
but low and zero for longitudinal shrinkage and T/R ratio. Phenotypic correlations between traits were weak suggest possibility for selection of families or individuals having good growth and desired wood qualities for further improvement improvement activities.