This research was carried in order to determine theyield components of four sunflower hybrids (Helianthus annuus L.) which differed in plant height. The hybrids were grown in three variants of plant population. The research lasted for two years, 1991 and 1992, and it was conducted at the Thrace Agricultural Research Institute in Edirne, Turkey. Experiments were established in a split- plot arrangement in RCBD, in four replicates. The hybrids used in the experiments were two semidwarf hybrids, Sunbred- 265 and DO- 855, a standard height hybrid Trakya- 259 and a tall hybrid Tordillo. The three plants populations were a high population (71430 plants/ha; 70 x 20 cm), a standard population (47620 plants/ha; 70x 30 cm), and a low population (35710 plants/ha; 70 x 40 cm). Both plant height, and population were found to have a significant (P<0.05) effect on seed yield components. According to the two-year results, the semidwarf hybrids had 8.4 and 18.8% higher seed yields in the high population than in the standard and the low population, respectively. For the standard and the tall hybrid, however, the standard plant population of 47620 plants/ha (70 x 30 cm) was determined as most suitable for high seed yield and oil yield per hectare.