A thermistor airflow sensor assembly adapted to be mounted adjacent the mouth and nose of a patient for monitoring the breathing of the patient, with the assembly comprising thin, flexible, resilient layers of film adhesively secured to each other to form a laminate. Copper conductor strips are formed by etching away a copper layer attached to the lower film prior to lamination, with chip thermistors being soldered to the copper conducting strips. The thermistors are mounted in leg portions extending laterally from a main body strip of the assembly, with two legs being adapted to be aligned with the nostrils of the patient, and the opposed leg extending downwardly to a position where the outer end thereof is generally aligned with the mouth of the patient. The copper conducting strips extend through an enlarged end portion of the assembly for electrical connection to a cable, a bend relief cable, and a plug which can be connected to a monitor for providing visual and/or audio alarm signals when breathing has been interrupted. A separate carrier strip can be mounted on the film layer adapted to be positioned against the face of the patient, whereby the thin flexible assembly can be easily adapted to the facial configuration of the patient. The entire assembly, including adhesive and the copper conductor strips, is in the range of 0.006"-0.008" in thickness, except for the thermistor locations and the strain relief area.