Three types of free-living aerobic nitrogen-fixing bacteria, namely, Azotobacter chroococcum, an yellow variety of Az. chroococcum and Beijerizzckia indica, were found in seven different agricultural soils of Hupeh Province. Az. chroococcum was the most widely distributed type. B. indica was found chiefly in the acid red-yellow soil. The yellow variety of Az. chroococcum was found only in the paddy soil developed from the acid red-yellow soil