In order to study genetic diversity, geographical distribution and relationships among seed yield and some morphological characters in common bean, 576 accessions were selected from the gene bank of the agricultural college, university of Tehran. The accessions were planted in the field in 1997 in rows with 5m length and 1 m apart. Cultivars Yas and Goli were planted every 24 rows as controls. The traits, seed number per plant, seed yield, pod weight, number of filled pods, biological yield, plant height and number of nodes on the main stem exhibited a high variability. Cluster analysis for geographical distribution grouped in 7 clusters. No relationship was found between genetic diversity and geographical distribution. The results showed that pod weight, number of pods, seed number per plant, 100-seed weight, number of nodes on the main stem, plant height and harvest index had the greatest effect on seed yield. In path analysis for seed yield, the weight and number of pods had high direct effect on yield while the direct effects of biological yield and seed number per plant were negligible thus; the highest impact was due to their indirect effect through pod weight. In path analysis for pod weight, number of pods had the highest direct effect (0.79). Harvest index and seed number per pod had indirect effects through pod number on pod weight. In general, correlation analysis of biological yield indicated that number of nodes on the main stem was highly and directly effective in increasing yield.
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