Agronomic and varietal trials of sunflower hybrids have been carried out both by extension officers, researchers and farmers. The objectives of these trials have been.- (1) to test adaptability of sunflower hybrids to different environments and (2) to examine whether hybrids tested are promising for extension program. Agronomic trials in farmers' fields at Petchaboon showed that tillage did not substantially affect sunflower grain-yield either with or without fertilizer. Of course, fertilized sunflower yielded greater than unfertilized one (352 VS 288 kg./rai). At Srisaket, no yield different between Hysun 33 and S.101 (perviousty called G.101) was found (274 VS 257 kg/rai). In contrast, yields of Hysun 33, from farmers' fields, were 280-350 kg/rai at Namaow district and 140-210 kg/rai at Chondan district whereas S.101, at Wichienburi, yielded as low as 80-97 kg/rai. Lower yields of S.101 resulted from unsuitable soil for sunflower. Varietal trials have also been conducted in six different research stations covering the two regions, the NE (3) and the N (3), Fertilizer treatments have been included as well in some of the stations. The seven-hybrids tested were Veraflor, Rustiflor, Maryflor, Cerflor, Topflor, S.101 and Hysun 33. The first five hybrids were from France and the last two hybrids were from the USA. and Australia, respectively. Results from the NE. were not incentive. Yields of sunflower ranged from 17.8-92.7, 89.3-234 and 69.6-96.9 kg./rai at Khonkaen, Srisaket and Mahasarakarm, respectively. Sunflower hybrids were not quite responsive to fertilizer, except for at Mahasarakarm, though averaged yields were low. A contrasting picture of the performance of sunflower hybrids was obtained from the N. region Grain yield of sunflower ranged from 31.1-205,277-560 and 266.61-420 kg/rai at Chiangmai FCRC, CMU (Hysun 33 and S.l0l excluded) and Sukhothai FCRS, respectively. Generally, Hysun 33 and S.l0l yielded greater than the other hybrids in four out of six research stations. The results suggested that Hysun 33 and S.l0l are the promising hybrids. to be included in the extension program.