Abstract: A spirometer having a turbine transducer which includes a plurality of blades past which exhaled or inhaled air can be blown on sucked to cause a degree of rotation of the blades in proportion to the volume of air passing at a speed proportional to the rate of flow of the air. The turbine transducer produces a series of electrical pulses preferably by an electro-optical sensor at a rate proportional to the rate of rotation of the blade and these are fed to a microprocessor which stores and processes pulses and displays information relating to pulmonary functions calculated in the microprocessor. It is preferred that the turbine transducer is housed in a body that can be held in the hand of and raised to the mouth of a patient and is constructed in such a manner and of such materials as to make it readily dismountable for cleaning while responding quickly and accurately to changes in the rate of flow of exhaled or inhaled air.