The respiratory abilities of a group of 19 speech-disordered subjects with idiopathic Parkinson's disease were assessed using both spirometric and kinematic techniques and compared to those of a group of 19 nonneurologically impaired controls matched for age and sex. Results of the spirometric assessment showed that only a minority of the Parkinson's subjects had lung volumes and capacities outside normal limits. Consequently in the majority of eases, the speech disorder could not be related to any abnormality in lung function determined spirometrically. Chest wall dynamics during both conversation and reading were essentially normal in all cases. Approximately half of the Parkinson's subjects, however, exhibited irregularities in their chest wall movements while performing vowel prolongation and syllable repetition tasks. The same irregularities were not present in the chest wall movements exhibited by the control subjects, suggesting that their presence was in some way related to the Parkinson's disease. Results are discussed in terms of the effects of Parkinson's disease on neuromuscular function.