This study was conducted to evaluate the effect of seed Rhizobia-treating and Cowpea severe mosaic virus (CPSMV) inoculation on bacterial nodulation and nitrogen fixation in cowpea. CPSMV was isolated from infected plants, College of Agriculture, Abu-Ghraib, Baghdad, IRAQ, the Rhizobia was isolated from nodules on roots of cowpea plants. The plants were inoculated by the virus 2 weeks after germinations. Nodules on roots of Rhizobia-treated plants were formed while no nodules were observed on non-treated ones. The mean number of nodules was 24.93\ plant on virus inoculated plants compared to 59.86 nodules\plant on non-inoculated ones. Significant reduction in nodules weight was induced by the virus, 0.62 gm on the virus inoculated plants compared to 2.13gm on non-inoculated ones. It has been found that the Rhizobia induced significant increase in nitrogen percentage at p=0.05 in the foliage, 1.29% in plants non-treated with Rhizobia non-inoculated by the virus compared with 2.502% in Rhizobia treated-virus inoculated plants and 2.550% in Rhizobia treated non inoculated plants. The virus caused an increase in nitrogen percentage, 1.877% compared to 1.29% in non-inoculated plants. The Rhizobia caused an increase in pods number\plant, seed number\plant, and seed dry weight (gm)\plant, 25.6, 114, 32.4 compared to 12.8, 70.6, 8.7 in non-treated plants respectively. The treatment of virus inoculated plant by Rhizobia induced a significant increase in these values, except with nitrogen percentage in seeds, 16.4, 84.6, 10.4, 4.3 respectively.