Flax ( Linum usitatissimum L.) is an oil seed crop and its seeds contain 40-45 % oil. Based upon the genotype, flaxseed oil is used as industrial or edible oil. Genetic variation and determining the relationships among the traits can be used in breeding programs of flax to select the desirable genotypes for seed yield. In this experiment, 19 genotypes of flax were evaluated in a randomized complete block design with 3 replications in 1392 at the Agricultural Research Station, Isfahan University of Technology to study the agronomic traits and the relationship among seed yield and its components. The results of analysis of variance showed that there were significant differences among the genotypes for most of the studied traits, including seed yield per plant and per plot and its components such as capsules per plant and seed weight. Relatively high phenotypic and genotypic coefficients of variation were estimated for days to maturity, number of branches per plant, capsules per plant, seeds per capsule, seed yield per plant and seed yield per plot. Moderate to high broad-sense heritability was observed for all of the traits (from 53/9% for capsules per plant to 98/9% for seed yield per plot), except for seeds per capsule (16/1%). Number of branches per plant, capsules per plant and seed weight highly and positively correlated with seed yield per plant. Also, both seed yield per plant and branches per plant had high and positive correlation with seed yield per plot. The results of stepwise regression showed that seeds per capsule, capsules per plant and seed weight totally contributed in 91% of the observed variation for seed yield per plant. The path analysis showed that seeds per capsule had the highest direct effect on seed yield per plant. Also, number of capsules per plant and seeds per capsule showed positive direct effects on seed yield per plot. Cluster analysis divided the genotypes into 5 distinct groups that the genotypes of two groups had high seed yield per plant and per plot. Generally, the results of this study showed that there was genetic variation for most of the traits that can be used for their genetic improvement, and the yield components of seeds per capsule and capsules per plant can be considered as selection indices in breeding programs to improve seed yield.