Four center pivot systems naming CPS1, CPS2, CPS3 and CPS4 were evaluated for improving water distribution uniformity during year (95/96). The selected systems covered areas ranged from 2 fed to 150 fed. Water distribution uniformity DU, coefficients of uniformity of Cri­tiansen CU_E, Wilcox and Swailes CU_w, Benani and Hore CU B, coefficient of variance CV and both of the application effeciency AE and system ef­ficiency SE were studied. It was found that average value of uniformity coefficient CU_a of CU_E and CUB can be considered as a suitable parame­ter to evaluate CP system under Egyptian conditions, in addition of coef­ficient of variation CV. Results indicated that the change of distribution uniformity Du ranged from 3% to 13% was due to operating the tested systems for two seasons. The change in the average uniformity coeffi­cient CU_a ranged from 0.7% to 8.9% resulting in the system efficiency changed from 8% to 13% depending on the amount of water applied (under 100% of setting speed). System maintenance specially after each season is essential to maintain high efficiency of the CP systems. Paper presented the most constrains which limited the expansion of CP system in Egypt.