Sheath blight disease, caused by Rhizoctonia solani, is a major fungal disease of rice, occurring mostly in Asian rice. The present study was performed to identify the chitinase polymorphism in 19 Iranian rice cultivars by using RFLP-PBR, with Rsa I, Taq I, Sac I and Ava I restriction enzymes. Digestion of the chitinase gene RICCH-3 by its specific digesting enzymes, i.e. RsaI and TaqI, produced a uniform banding pattern in all the rice cultivars studied. However RICCH-1 digestion showed banding pattern polymorphism in the two cultivars 1205 and 1206 and digestion of RICCH-2 showed banding pattern polymorphism in the cultivars 665 and 667. The cultivars studied showed no polymorphism for the sites of the AvaI and SacI enzymes. In total, 13 bands were obtained by the digesting action of RsaI and TaqI enzymes among 19 rice cultivars studied, 4 bands were common in all the cultivars while one unique band was observed in the cultivar 326. There were 4 other bands present in all other cultivars but missing in the cultivar 326, making this cultivar significantly different from the other rice cultivars studied. Data obtained suggested the possible occurrence of intra-geneic deletion in the RICCH-1 site and intra-genic duplication in RICCH-2 site. Grouping of the rice cultivars on the basis of the RFLP bands obtained did not correlate with their geographical regions of cultivation. This is the first report on chitinase polymorphism in Iranian rice cultivars.