Patients undergoing relatively minor surgery under spinal or epidural anesthesia alone occasionally request sedation or sleep during surgery and certain sedatives such as midazolam or propofol are administered intravenously. The study evaluated the applicability and safety of using nasal BI-PAP and low-dose propofol sedation as an adjunct to spinal anesthesia during herniorrhaphy. Twenty-five adult patients undergoing repair of inguinal hernia under spinal anesthesia received propofol infusion for sedation with the assist of noninvasive positive-pressure ventilation (NPPV). Circulatory and respi-ratory parameters, such as percutaneous oxygen saturation, transcutaneous carbon dioxide tension, respiratory rate, tidal volume, blood pressure, and heart rate, were maintained within accepted ranges during anesthesia. There were no adverse effects. These findings suggest that the application of NPPV in patients receiving propofol infusion for sedation is clinically practicable during anesthesia.