In the present study, four isolates of Azotobacter paspali were isolated from rhizosphere of maize and wheat plants and tested their Nitrogen fixing ability after treatment with Mancozeb. It was observed that the lower concentration of Mancozeb (1gm/L) increase growth of Azotobacter species while at a concentration of 4gm/L, all cells died. The concentration of 2gm/L and 3gm/L decreased the no. of cells and Nitrogen fixing capacity of Azotobacter was decreased by 50%.