This study was carried out to estimate the broad-sense heritability for seed yield and some yield components of 15 grass pea (Lathyrus sativus L.) genotypes in 2000-2002 at Bursa, in the Marmara region of Turkey. The experimental design was a randomized complete block design with 3 replications. The heritabilities for seed yield, plant height, pod number, seed number per pod, seed number per plant, 1000-seed weight, biologic yield, and harvest index were estimated as 30%, 42%, 61%, 19%, 56%, 75%, 82%, and 49%, respectively. It was found that biologic yield was the trait least affected by environment, followed by 1000-seed weight. On the other hand, seed number per pod, harvest index, seed yield, plant height, seed number per plant, and pod number were the traits affected most by environmental conditions. According to the results, the biologic yield and 1000-seed weight could be used as selection criteria in early generations.