Simazine is one of the more important olive selective residual herbicide. The paper shows the possibilities of simazine root absorption in four olive varieties 'Alfafara', 'Arbequina', 'Blanquilla' and 'Villalonga'. The treatments were made by subherbigation at two rates 1 ppm or 6 ppm. Samples of shoots were taken and analysed at different times after the treatments and olives were harvested. The results show that simazine and des-alquil simazine was detected one time, but only at the higher rate. No herbicide resi­due was detected in the oil.