Breathing was investigated in 14 male subjects with Parkinson's disease and 14 healthy male control subjects. Kinematic, spirometric, acoustic, and pressure data were used to assess function during resting tidal breathing, reading aloud, and monologue production. Data were collected at two times during the drug cycle for subjects with Parkinson's disease. During resting tidal breathing, subjects with Parkinson's disease, on average, had a faster breathing rate, greater minute ventilation, and smaller relative contribution of the rib cage to lung volume change than did healthy control subjects. During speech breathing, rib cage volume was smaller and abdominal volume was larger at initiation of the breath groups for subjects with Parkinson's disease than for healthy control subjects. Subjects with Parkinson's disease produced fewer words and spent less time producing speech per breath group and tended to have a faster interpause speech rate than did healthy control subjects. There was no difference between groups for duration of inspirations between speech breath groups. Oral pressure was lower for subjects with Parkinson's disease but estimated tracheal pressure did not differ between the two subject groups. Few differences were found between the two times in the drug cycle for resting and speech breathing. Results provide indirect evidence for reduced relative compliance of the rib cage to the abdomen for subjects with Parkinson's disease as compared to healthy control subjects. In addition, the results support the possibility of inadequate valving of the air stream for subjects with Parkinson's disease.