Purpose: To examine the influence of visual information on speech intelligibility for a group of speakers with dysarthria associated with Parkinson's disease. Method: Eight speakers with Parkinson's disease and dysarthria were recorded while they read sentences. Speakers performed a concurrent manual task to facilitate typical speech production. Twenty listeners (10 experienced and 10 inexperienced) transcribed sentences while watching and listening to videotapes of the speakers (auditory-visual mode) and while only listening to the speakers (auditory-only mode). Results: Significant main effects were found for both presentation mode and speaker. Auditory-visual scores were significantly higher than auditory-only scores for the 3 speakers with the lowest intelligibility scores. No significant difference was found between the 2 listener groups. Conclusions: The findings suggest that clinicians should consider both auditory-visual and auditory-only intelligibility measures in speakers with Parkinson's disease to determine the most effective strategies aimed at evaluation and treatment of speech intelligibility decrements. (Contains 2 tables and 1 figure.)