In microcosm set-ups we investigated whether combined releases of the predatory thrips Scolothrips longicornis Priesner and two phytoseiid species, Neoseiulus californicus (McGregor) and Typhlodromus bagdasarjani Wainstein & Arutunjan provide better biological control of Tetranychus urticae Koch on cucumber plants than releases of each predator species alone. Results showed that control of T. urticae populations was equivalent under all predator combinations as in single predator release, indicating that no additive or synergistic effects among three predatory species had occurred in the control of the prey. In addition, the densities of each predator species under different combinations were similar, indicating that the three predators did not prey on each other during the observation period. Overall, our results showed that all three predator species are effective predators of T. urticae under microcosm conditions and suggest that they can be used in combination without decreased efficacy through intraguild predation.