The western flower thrip, Frankliniella occidentalis (Pergande) poses a significant risk to many food and ornamental crops in the Mediterranean region of Turkey. Chemical control has been the primary means used to control the population of F. occidentalis in protected cultivation systems in Turkey. We evaluated Amblyseius swirskii (Athias-Henriot) on peppers following single releases at the rate of 50 adults per m 2 as a predator of F. occidentalis in heated and unheated plastic tunnels. The study covered the period when the peppers had started to flower. In both tunnel types, despite greater variation in day/night temperatures in unheated plastic tunnels, the F. occidentalis population was maintained at a level of fewer than 2 per flower throughout the experiments in plots where predatory mites were released. The density of the thrips infestation exceeded the action threshold of 3 thrips per flower in control plots. The results of the study show that A. swirskii is highly effective for controlling western flower thrips on sweet pepper and can provide long-term thrips control. In the eastern Mediterranean region of Turkey, pepper growers who are considering releases of this predatory mite in plastic tunnels may find A. swirskii useful as a new control agent.