Flax ( Linum usitatissimum L .) is a widely adapted oilseed crop with several desirable attribute and multiple uses that its seed, oil and crushed-seed meal are being used in different industries, in human diet and feeding of the livestock. In order to develop the improved cultivars of flax, it is necessary to investigate genetic variation of the traits. To study the agronomic traits, yield components and their genetic variation, 24 families in F 4 generation were evaluated in a randomized complete block design with three replications in 2015 at the Agricultural Research Farm of Isfahan University of Technology. The results showed that there were significant differences among the families for all studied traits including, number of base branches per plant, number of capsules per plant, number of seeds per capsule, 1000-seed weight, seed yield per plant and seed yield per unit area. Seed yield per plant and seed yield per plot among the families ranged from 0.17 to 0.54 gr and from 764.4 to 2067.2 kg/ha, respectively. Also, the results showed that the phenotypic and genetic coefficient of variation for number of days to 50% emergence, number of branches per plant, number of capsules per plant, seed yield per plant and seed yield per unit area was high, indicating that there was a considerable genetic variation for these traits among the F4 families. Moreover, relatively high broad-sense heritability (between 59.02 to 91.53%) was observed for the traits of days to flowering, days to maturity, number of branches per plant, number of seeds per capsule and seed yield per unit area. Generally, the minimum and maximum broad-sense heritability was observed for capsules per plant and days to 50% flowering, respectively. Seed yield per plant had a high positive correlation (r=0.80 ** ) with number of capsules per plant. Also, seed yield per unit area showed a high positive correlation (r=0.50 * ) with seed yield per plant. Based on the stepwise regression analysis, number of capsules per plant, number of seeds per capsule and 1000-seed weight were in order the most important components of seed yield per plant, and they contributed in 83% of its variation. The path analysis showed that the number of capsules per plant had the most direct effect on seed yield per plant, and it can be used as a selection criterion to improve the seed yield. Cluster analysis Keywords : Fax, Genetic variation, Broad-sense Heritability, Agronomic Trait