Abstract: A sand culture experiment was carried out during 2002-2003 to evaluate the effect of different levels of salinity on some metabolic activities and yield of three mustard genotypes viz., Safal, Binasarisha-4 and Binasarisha-5. The salinity treatments were EC0 (control or no salt), EC5, EC10 and EC15 dS m-1. Results reflected that salinity treatment caused decrease in NR activity and reduced the accumulation of chlorophyll, nitrate, amino acid, soluble protein and sugar. Root volume and weight and the accumulation of potassium and zinc were decreased while nitrogen, phosphorus and sodium accumulations increased. Genotypes Safal and Binasarisha-5 had higher accumulation of almost all the biochemical and chemical substances compared to Binasarisha-4 at salt stress condition. In all the genotypes of mustard yield was reduced at salt stress condition. But in genotype Safal dry matter accumulation and seed yield were better than those of the other two. From the above results it was indicated that Safal and Binasarisha-5 performed better with respect to biochemical point of view as well as yield under salinity stress.