study was conducted to determine the effects of different seeding rates on yield and quality characteristics of fennel without using any chemical fertilizers and pesticides, in Atabey-Isparta ecological conditions during 2010 and 2011 vegetation periods. The experiment was established as randomized blocks design with three replications and three seeding rates (10, 15 and 20 kg ha(-1)) were applied. Plant height, fruit yield and biological yield were significantly affected by seeding rate. Fruit yields ranged between 230.35 and 790.96 kg ha(-1) and the highest yield was obtained from 15 kg ha(-1) seeding rate. Essential oil contents ranged between 1.60 and 2.46%. The main constituent of the essential oil was identified as trans-anethole ranged between 84.48% and 97.79%.