Exposure assessment is a critical point for epidemiological studies on pesticide health effects. PESTEXPO study provides data on levels of exposure and their determinants in real conditions of pesticide use. We described levels of exposure in vineyards during treatment tasks (mixing, spraying and cleaning) and we analysed their determinants. Sixty-seven operators using dithiocarbamates or folpet were observed. Detailed information on the tasks (general conditions, operator, farm and equipment characteristics) were collected and dermal contamination was measured, using patches placed onto the skin on eleven body parts, and washing the hands at the end of each phase. The spraying phase represented roughly half of the contamination, whereas mixing and equipment cleaning accounted for 30% and 20% of the contamination, respectively. The main determinants of exposure were the number of phases, the characteristics of the equipment, the educational level of the operator and his status (farm -worker or -owner) and the general characteristics of the vines. Algorithms were built to estimate daily external contamination, according to these characteristics during mixing, spraying or equipment cleaning. With additional information of frequency and duration of use, they will enable to develop exposure indices usable in epidemiological studies on farmers' health.