Results of a field study on the efficiency of vapor recovery systems currently used in gasoline service stations in Mexico City are presented. Nine gasoline stations were studied, representing the several technologies available in Mexico City. The test was applied to a fixed vehicular fleet of approximately 10 private and public service vehicles. Each one of the gasoline service stations tested reported efficiencies above 80% in the recovery of vapor losses from gasoline which is the minimum permissible value by Mexican regulations. Implications to the emissions inventory are discussed. A second goal of this study was to measure the potential exposure of service attendants to three important components of gasoline: benzene; toluene; and xylenes. The influence of spatial location of personnel within the service station was also evaluated by measuring levels of the three compounds both at the refueling area and in the service station office. Results are discussed and compared to a previous study.