Greenhouse vegetable production has an important place in Turkey. Tomato is the most important crop in terms of production amount and cultivation area. Pests have caused problems in greenhouse horticulture as in all agricultural areas. Trialeurodes vaporariorum is one of the most important pests causing damages in production. The most common protection method is chemical one resulting in unconscious and extensive pesticide use. For this reason there is a need to study on sustainable protection tools in order to improve alternatives due to the increase of environmental awareness during the last decade. This preliminary study was conducted to determine the effects of repellent plants on whitefly population in greenhouse tomato production. Seven repellent plants namely basil (Octimum basilicum), mint (Mentha avensis), dill (Anethum graveolens), garlic (Allium sativum), onion (Allium cepa), parsley (Petroselinum crispum) and cilantro (Coriandrum sativum) were grown with tomato plants and control treatment without any repellent plant was included. In every plot there were 12 tomato plants with 4 replications. First the seeds of repellent plants were sown and then tomato seedlings were planted. T. vaporariorum (320 adults and 225 pupae) were released to the greenhouse. Plants were counted twice a week after pests were implicated. The average population intensity in every leaf was found as; basil 0.90; mint 0.68; dill 1.20; garlic 0.23; onion 0.80; parsley 0.61; cilantro 0.16. It was concluded that cilantro due to the whitefly population intensity was found promising among the tested repellent plants and could be used in commercial production.