Biological control of Thrips tabaci was studied on greenhouse grown cucumbers by using predatory mite, Amblyseius cucumeris. Trials were conducted on cv. Kahya of cucumber in 1995, and on cv. Kahya and cv. Ozde in 1996. In both years plot size consisted of 3 rows of 40 plants for each predator release and non-release control plots. Predators were released at a rate of 4-5 individuals per plant as soon as thrips were detected on host plants.