Eleven Italian ryegrass cultivars were examined for their genetic polymorphisms and phylogenetic relationships using randomly amplified polymorphic DNA (RAPD) markers. In RAPD analysis of 34 random primers, 96 of total 162 bands obtained from 16 primers were polymorphic and sizes of polymorphic band ranged between 0.5 and 1.5kb. Number of bands amplified per primer was varied from 3 to 16 and average number was 14.8. Phylogenetic relationship among cultivars based on the RAPD analysis was examined using UPGMA computer program. In pairwise genetic similarity test of 11 Italian ryegrass cultivars, Grazer and Orlando showed highest coefficient of genetic similarity as 0.740, whereas Marshall and Orlando was lowest as 0.438. Eleven Italian ryegrass cultivars were grouped into 3 major clusters and genetic distance of clusters ranged between 0.567 and 0.646, indicating low level of genetic variation.