This research was carried out to determine some agronomical characters and the hybrid performances for these characters of new-improved synthetic sunflower varieties (SYN.-1(A), SYN.-1(B), SYN.-1(C) and SYN.-1(D)) during the years 1994-1997 at the Experimental and Research Farming of Faculty of Agriculture, Uludaǧ University. In the first year (1994), the synthetic varieties were obtained by open pollination from the mixture of the inbred lines (SYN.-0(A), SYN.-0(B), SYN.-0(C) and SYN.-0(D)) forming each of the synthetic varieties. In the second, third and fourth years, four synthetic varieties, four mixtures of the inbred lines and two standard varieties (Vniimk-8931 and one commercial hybrid) were tested in a randomized block design with four replications in non-irrigated conditions. According to the three-year results of the research, the mean values of the characters in synthetic varieties varied between 149.7 and 154.4 cm for plant height: 15.4 and 16.7 cm for head diameter; 718 and 869 unit for the number of seeds/head; 53.9 and 56.5 g. for 1000 seed weight; 40.2 and 46.8 g. for seed yield/head and 1847 and 2114 kg/ha for seed yield per hectare. It was found that the synthetic varieties showed 8.0 to 13.4 % heterosis for plant height; 12.2 to 16.7% for head diameter; 31.2 to 43.0% for the number of seeds/head: 2.0 to 25.0% for 1000 seed weight: 38.1 to 72.4% for seed yield/head and 46.1 to 78.9% for seed yield per hectare. Synthetic-1(A), Synthetic-1(C) and Synthetic-1(D) had 15.4%-19.0% greater seed yield as compared to the standard variety, Vniimk-8931. It was found that the varieties Synthetic-1(A), Synthetic-1(C) and Synthetic-1(D) were of the same yield capacity as the commercial hybrid variety.