Tomato (Solanum lycopersicum L.) is one of the most important vegetables, whose production and consumption increased quite rapidly. The effect of three insecticides (alpha-cypermethrin, chlorpyriphos and pirimicarb) on seed germination and seedling growth of this species has been studied, based on morphological parameters monitored and by using four dilutions of the normal concentration used in agriculture (100%, 75%, 50%, 25%) for germinating seeds, and only the recommended concentration in agriculture for growing plants. The results show that the three insecticides induced a delay of germination and growth process. The germinated rate of seeds treated was lower compared to control, and the length of roots and shoots in treated seeds and plants was reduced. Key words: Insecticides, Tomato, Solanum lycopersicum, Germination, Growth.