A novel CMOS-process-compatible MEMS sensor for monitoring respiration is presented. This resistive flow sensor was manufactured by the TSMC 0.35 ¿m CMOS/MEMS mixed-signal 2P4M polycide process. The sensor was demonstrated to be sensitive enough to detect the respiratory flow rate, and the relationship between flow rate and sensed voltage is quite linear. If one can integrate the sensor with its sensing circuit into a single chip, the cost of a pneumotach system can be greatly reduced. Moreover, the proposed sensor is useful in both invasive and noninvasive applications.