Genetic diversity among thirty-nine “new plant type” tropical japonica lines and three improved cultivars was studied using Mahalanobis D² statistic. The genotypes were grouped into 14 clusters. Cluster I with 14 genotypes was the largest while cluster IX, X, XI, XII, XIII, XIV were monogenotypic. Genotypes in cluster II had the highest intra cluster distance. The maximum inter cluster distance (1328.30) was recorded between cluster VI and VII. Harvest index contributed maximum (45.99 %) to the total divergence. Other traits with appreciable contribution to total divergence were biological yield per plant, grain number per panicle and 1000-grain weight whereas panicle length had no contribution towards total divergence. Hybridization among genotypes IR 66736-75-1-3, IR 66792-23-1-2-2, IR 69810-62-1-3, WCR 6 and Govind drawn from widely divergent cluster is likely to produce heterotic combinations and wide variability in segregating generations.