This research was conducted to evaluate the genetic diversity of Sainfoin ( onobrychis viciifolia Scop) half-sib progenies, derived from two populations with natural and induced variability. Also it was aimed to provide better understanding of factors affecting interrelation between the characters and identify the best combiner parents from both mutated and non-mutated populations. Considerable variation was observed in the two populations for fresh and dry forage yield, dry matter percentage, persistency and powdery mildew susceptibility. Except for dry matter percentage in the second year, phenotypic and within population coefficients of variability didn’t show significant differences between the two populations during two years. Results showed that there were significant differences between mutant and non-mutant families for number of stem per m 2 , plant height, leaf to stem ratio, dry matter percentage and spring growth. Mutant families were superior for leaf stem ratio while non-mutant families were better for other characters. Family by year interaction was significant for all characters except plant height. Result showed that general combing ability (GCA) was significantly different between mutant and non-mutant populations for most of the traits. Ward cluster analysis based on general combining ability grouped mutant and non-mutant families separately in four clusters. Based on important traits, a number of mutant (8, 9, 10, 11, 12, 13, 18, 36, 39 and 40) and non-mutant genotypes (1, 3, 5, 6, 7 and 9) were selected as the best parents for developing synthetic variety. Mutation changed relationships between some of characters. For example correlation of dry forage yield with number of inflorescence was negative in non-mutatnt and positive in mutant families. Correlation of leaf percentage with number of stem per plant was positive in mutant but negative in non-mutatnt families. Factor analysis showed that mutant families with fewer factors explained greater variance than non-mutant families. Results of cluster analysis confirmed the high genetic variability in each population. A group of genotypes clustered together in mutant population stayed roset and did not grow in the first year indicating a possible induction of vernalization requirement in these genotypes. In conclusion, the results indicated that there was a broad genetic diversity in mutant and non-mutatnt populations which can be exploited in future breeding programs. Key Words : General combining ability, Mutation, Variation, Sainfoin, Phenotypic correlation