The effects of the processing steps on some pesticides during physical refining of olive oil were determined. Oil samples were spiked with four types of pesticides, i.e. endosulfan (alpha-endosulfan, beta-endosulfan and endosulfan sulphate), simazine, oxifluorfen and diflufenican, and subjected to physical refining (bleaching and deodorization). The removal of contaminants by bleaching earths was compared using five types of commercial earths. Deodorization assays under laboratory (10 kg) and discontinuous pilot plant (200 kg) conditions at different temperatures and treatment times were carried out. Bleaching seemed effective only for the elimination of simazine. For removal of the other pesticides tested, a physical refining treatment was required at 240 degrees C in the deodorizing stage for different periods (1 h for diflufenican, oxifluorfen and alpha-endosulfan, 2 h for beta-endosulfan and 3 h for endosulfan sulphate).