This study aimed to investigate genetic and environmental ef­fects on seed yield and seed quality characters of lentil. Eeight field ex­periments were carried out at four research stations in Egypt in 1997-98 and 1998-99 seasons with 24 diverse lentil genotypes. The studied characters were: seed yield (kg/fed), number of pods and seeds/plant, 100-seed weight, seed protein content, hydration coefficients of seeds before cooking (H.C.B.) and after cooking (H.C.A.) and seed cookability. There were highly significant differences between genotypes, locations and genotype x location interaction for all studied characters, with great environmental (location) effects. On the basis of the relatively high herit­ability, coefficient of genetic variation and genetic advance, pronounced progress should be expected from selection for 100-seed weight. Moder­ate progress from selection among genotypes should be expected with number of seeds/plant. However, lower genetic advance should be ex­pected from selection among genotypes for seed yield, H.C.B., number of pods/plant and seed protein content.