The objective of this study was to investigate the effect of various sowing rates on seed yield of lentil. Field experiments were conducted for three consecutive years (2001-02 to 2003-04) at the National Agricultural Research Centre (NARC), Islamabad, Pakistan during the lentil growing season. An improved medium-grain size (1000-grain weight. around 25 g) variety Masoor 93 (18-12 x ILLP 4400) was used in these experiments. Eleven seeding rates i.e., 14.0, 21.25, 28.50, 35.75, 43.0, -1 50.25, 57.50, 64.75, 72.0, 79.25 and 86.50 kgha were evaluated in the study. Results of the three-year study showed that grain yield kept on -1 increasing up to a seed rate of 43 kgha and remained static thereafter with a non-significant difference for any further increase in seed sown. The -1 existing seed rate of 20 kgha in lentil is seemingly not sufficient to obtain optimum yield. On average, about 2-2.5-fold increase in seed rate of lentil under rainfed conditions can be safely recommended.