Flame retardant finish of cotton fabrics was carried out using N-methyloldimethylphosphonopropionamide(MDPPA) in conjunction with nitrogen compounds such as hexamethylolmelamine(HMM) and dimnethyloldimethoxyethylene urea(DMDMEU). The effects of nitrogen compounds on the flame retardancy and strength retention(tensile and tearing) of the treated fabrics before and after laundering were investigated. The results obtained are as follows; Flame retardancy increased with the concentration of MDPPA. Durable flame retardancy after 50 laundry cycles could be obtained when MDPPA concentration was more than 40%. Nitrogen compounds used with MDPPA enhanced flame retardency and durability to laundering. Among the three types of nitrogen compounds, i.e., HMM, DMDMEU, and HMM/DMDMEU(1/1) mixture, mixture of HMM/DMDMEU(1/1) was most effective to enhance flame retardency and durability. Tensile strength retention of treated fabric increased slightly with the amount of nitrogen compound. But tearing strength retention was not significantly affected by the types and the amount of nitrogen compound.