The study aimed to investigate the effect of plant density (200, 300, 400 and 500 plants/m²) on the economic lentil characters of the new released varieties Sinai 1, Giza 4 and Giza 51 in comparison with the old variety Gin 9 at north and south Egypt A field experiment was carried out at Gemmiza (Middle Delta) and Mattaana (Upper Egypt) research stations in 2001/2002 and 2002/2003 seasons. Significant differences occurred among plant densities, varieties, and locations. 400 plants/m² produced the maximum yield/feddan, surpassing the yield of 200 plants/m² by 40.7 and 23.4% at Gemmiza and Mataan, respectively. The variety Gin 4 at 400 plants/m²gave the highest seed yield at Gemmiza (5.19 ardab/fed) and Mataana (3 89 ardab/fed). Although low plant density of 200 plants/m² gave more branches, pods, seeds and seed weight/plant over all other plant densities, it was outweighed by the effect of population gradients on those characters and hence high plant density produced high seed yield/feddan. With consideration to differences in seed size among varieties, and the significance of variety x plant density interaction, the densities 300 plants/m² for Sinai 1 and 400 plants/m² for other varieties are recommended for higher yields of lentil. The equivalent seed rates/feddan are 45kg for Sinai 1, 37kg for Gin 4 and Giza 9 and 42kg for Gin 51.