Purpose. To assess the effect of a self-paced walking intervention within a topographically varied outdoor environment on physiological and perceptual markers in cardiac rehabilitation (CR) patients. Methods. Sixteen phase II CR patients completed twelve self-paced one-mile walking sessions over a four-week period within a community-based CR programme. Walking velocity, heart rate (HR), and ratings of perceived exertion (RPE) were reported at eight stages throughout the self-paced walks. Results. The study showed a significant increase in walking velocity from week 1 (~4.5 km/h) to week 4 (~5.1 km/h) of the self-paced walking programme (P < .05). A significantly higher HR was also observed in week 4 (111 ± 13 b·min(-1); ~69% of maximal HR) compared to week 1 (106 ± 14 b·min(-1); ~65% of maximal HR, P < .001). There were no changes in the average RPE across the course of the 4-week self-paced walking programme (P > .05). Conclusion. A self-paced walking programme may elicit an appropriate training stimulus for CR patients when exercising within a diverse topographical environment. Participants completed a one-mile walk within a shorter period of time and at a higher physiological intensity than that elicited at the onset of the programme, despite no observed changes in participants' subjective perception of exertion.