Minjiri (Cassia siamea Lam.) is a promising fast growing tree species indigenous to Bangladesh and is included in the plantation programme. An attempt has been made to prepare the biomass tables for the species. The biomass equations were selected to estimate the green weight of the whole tree, weights of the stem, the branches, leaves and twigs, branches and stem; branch, leaves and twigs. The diameter at breast height (D) – biomass and D-height – biomass relationships were determined. It was observed that the logarithmic function to the base “e” gives a good fit model. The conversion factors were also determined to estimate the air-dry and oven-dry weights of the components.