OBJECTIVE To evaluate the use of the laryngeal mask during general anesthesia. METHODS We prospectively studied patients undergoing surgery with general anesthesia in spontaneous breathing. METHODS Urologic and general surgical ward, with standard monitoring equipment. METHODS We studied consecutively 100 patients (ASA 1-3, 80 males, 20 females, age 64 +/- 15 years, range 19-98 years); 59 patients had a preexisting cardiopulmonary or metabolic disease. Monitoring included ECG, the arterial pressure (noninvasive), the CO2 capnography (EtCO2), the pulsossimetry (SpO2), the respiratory rate (RR) and the tidal volume/kg (TVi). The double product (DP = heart rate X systolic arterial pressure) was used as an index of cardiac stress. These parameters were recorded at 10-minute intervals throughout the procedure. RESULTS The heart rate, the systolic arterial pressure remained stable during the anesthesia, whereas the DP significantly decreased at t10, t20, t30 and t40. The EtCO2 decreased slightly (from 41 +/- 6 to a 36 +/- 4 mmHg; p.n.s.), SpO2 did not change (from 97 +/- 2% to 96 +/- 2%; p:n.s.). The RR significantly increased at t30 and t40 and the TVi significantly increased during the first hour. No relevant complications have been reported. CONCLUSIONS Anesthesia with laryngeal mask was not associated with any detrimental cardiovascular and respiratory effect.