This study examined the effects of concurrent walking tasks and interlocutor distance on conversational speech production in fifteen individuals with idiopathic Parkinson's disease (PD) and fourteen age-equivalent controls. Recent studies of speech in PD have demonstrated that changes in the behavioural conditions and the environmental context can have a powerful effect on the severity of speech symptoms in PD. This investigation focused on changes in speech intensity and speech rate in response to changes in walking speed and interlocutor distance. Results suggest that the introduction of a concurrent walking task significantly increased the conversational speech intensity of both controls and individuals with PD. When compared to sitting and talking or standing and talking, current walking and talking appeared to have an energizing effect on conversational speech intensity. In addition, walking faster was associated with a significant increase in conversational speech intensity relative to normal and slow walking speeds. These results provide important new information about the effect of concurrent walking on speech motor performance and speech symptom severity in PD. The potential energizing effect of concurrent walking conditions on conversational speech intensity may be an important consideration in the assessment and treatment of individuals with low speech intensity in PD.