Abstract: The capability of Urocystis agropyri as a bioagent to control ryegrass in wheat fields was examined. Non-significant difference between the wheat production sown in soil inoculated and non-inoculated with the isolate of U. agropyri, but highly differences were recorded when wheat and ryegrass sown together in soil inoculated and non-inoculated with this isolate. The results indicated that ryegrass had a significant negative effect on the productivity and yield components of wheat. The productivities of wheat were 2402 and 2362 kg ha-1 for only wheat sown in soil non-inoculated and inoculated with U. agropyri, while they were 1184 and 690 kg ha-1 for wheat and ryegrass sown in soil inoculated and non-inoculated with the isolate of U. agropyri, respectively. This confirms that ryegrass had a significant negative effect for wheat productivity and the isolate of U. agropyri can be used as a biological agent to control this weed in order to increase the productivity of wheat.