In this study, the effects of callus age, ultraviolet (UV) irradiation and incubation time were investigated for the induction of trans-resveratrol production in callus cultures of Kalecik karasi (Clone 12) Vitis vinifera L. grape cultivar. Part of leaves (similar to 1 cm(2)) were taken from one year old grapevines grown in greenhouse and then were cultured in Gamborg B-5 media including 2% saccarose, 0.8% agar, 1.0 mu M BAP (6-benzylaminopurine) and 0.1 mu M 2, 4-D (2, 4-dichlorophenoxy-acetic acid). After the second subculture, 12 and 15 days old callus tissues were exposed to 254 nm UV light at 10 cm distance from the source for 10 and 15 min. Trans-resveratrol was measured at 0, 24, 48 and 72 hours of incubation by using High Pressure Liquid Chromatography (HPLC). Trans-resveratrol concentration of control callus ranged from 0.56 to 0.96 mu g g fw(-1). The highest trans-resveratrol production was obtained from 12 and 15 days-old callus irradiated for 10 min. at the 48(th) hours of incubation (2.42 mu g g fw(-1)). Considering the highest value of trans-resveratrol concentration in controls and experiments, it was determined that UV irraditation in Kalecik karasi elicitated the trans-resveratrol production by 2.5 times.