Technical Abstract: Approximately 400 and 30 melon (Cucumis melo L) germplasm accessions collections were recently collected in India (1992) and China (1994), respectively, and incorporated into the U.S. National Plant Germplasm System. Genetic variation among 378 of these accessions was evaluated using 19 isozyme loci in 13 enzyme systems. These accessions were compared to two reference cultivars, 'Top Mark' and 'Green Flesh Honeydew' that represent the range of genetic variation in two distinct cultivar-groups of U.S. C. melo subsp. melo: Canalupensis and Inodorus, respectively. Statistics that define genetic variation (Nei's gene diversity, Shannon's information index, genetic distance, heterozygosity, and polymorphism) were calculated for comparative analysis. An initial cluster analysis resulted in 148 groups of varying size, ranging from two to 47 accessions. An accession from each of the 148 groups was chosen at random and used in a second cluster analysis that identified 11 isozyme groups. Group 1 was unique and consisted on only two C. melo subsp. agrestis accessions. Two large clades were separated at node 2. While one was comprised of three groups of 3, 12 and 34 accessions, the other clade had seven groups of 2 (two groups), 3, 14, 16 and 47 accessions, and included the reference cultivars. Of the 148 accessions, 132 were from 41 sites in Rajasthan and Madhya Pradesh, and were distributed unequally across the 11 groups. The 14 Chinese accessions originating from seven provinces were dispersed unequally in four cluster groups. 'Top Mark' and 'Green Flesh Honeydew' were genetically distinct and uniquely clustered in the same group. The variation among Chinese accessions was less than that detected in the Indian accessions examined; possible reasons for this are discussed. Additional collections of melon germplasm should be made in eastern and southern India.