Soil gas monitoring techniques (CO2, O2, 222Rn, 4He) are used in the geographical context of the recent volcanic system of Lake Pavin (Puy-de-Dôme), to get a better knowledge of local gaseous emissions, in order to establish if this system can present evidences of reactivation or not. Concentrations up to 100% CO2 and 50 ppm of helium are measured in a narrow geographical area (Escarot mofette), together with a magmatic origin for these gases. Radon activities in the mofette area are quite high, but do not show, compared to surrounding areas, enrichments as high as those measured for CO2 or helium. Hourly records of these radon activities, performed during several weeks, suggest the existence of pulsed radon exhalation in the mofette area. The period of this pulsation is around 40 days but its origin remains poorly understood. Apart from this mofette, no evidence of gas originated from depth is highlighted.