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In order to study the effects of plant density on agronomical characteristics of rice varieties a field experiment was carried out in field of Ghaemshahr Azad University in 2006. This experiment was laid out in split plot in basis of Randomized Completely Block Design with three replications. Main factor was rice variety in three levels (Hashemi Tarom, Fajr, Neda) and minor factor was planting density (Including 10 x 8.3, 10 x 10, 12.5 x 10, 16.6 x 10, 16.6 x 15 and 25 x 20 cm or 120, 100, 80, 60, 40 and 20 plant m (-2), respectively). Results showed that planting density had significant effect on plant height, total spikelets, total tillers, fertile tillers, panicle per m2, grain yield and harvest index. Days number till to 50% flowering stage and growth period length were maximum in Neda variety. Also these characteristics were not influenced by different planting densities. Maximum plant height and maximum panicle length were obtained in Hashemi Tarom variety and minimum of these characteristics were produced in Neda variety. Plant height was decreased significantly with increase of planting density.