Pualownia, one of the fast growing trees in the world, is being introduced in Pakistan. It can be propagated from seed and stem or root cuttings. Propagating from stem or root cuttings is important for producing genetically uniform planting stock. The stem cuttings are difficult to propagate as compared to root cuttings. This paper reports results of the study on determination of suitable size of paulownai root for vegetative propagation.