INTRODUCTION:Evaluating adherence to home-based pulmonary rehabilitation (PR) could be challenging due to lack of direct supervision and the complex nature of the rehabilitation model. To measure adherence to home-based PR in the HomeBase trial, participants were encouraged to work towards a goal of at least 30 min of whole-body exercise on most days of the week and report their participation using a home exercise diary. OBJECTIVE:This project aimed to evaluate the acceptability and validity of the home exercise diary. METHODS:Diary return and completion rates assessed acceptability of the home exercise diary. Home participants underwent physical activity (PA) monitoring using the Sensewear armband during the final week of an 8-week PR. The correlation between self-documented and objective daily exercise minutes was calculated. Objective exercise minutes were defined as bouts of ≥10 min spent in ≥ moderate PA. Differences in self-documented weekly exercise minutes between sufficiently active (≥7000 daily steps) and inactive participants were computed. RESULTS:Diaries were returned by 92% of programme completers. Of those who returned diaries, 72% have completed exercise documentation. Fifteen programme completers underwent PA monitoring [mean age 69 (9) (SD) years, FEV1 55 (19) %predicted]. A moderate correlation was observed between self-documented and objective mean daily exercise minutes (r = .59, P = .02). Active participants [n = 6, 10 253 (1521) daily steps] documented more exercise (111 min) during week eight compared with inactive participants [n = 9, 2705 (1772) daily steps, P = .002]. CONCLUSION:The self-documented home exercise diary is an acceptable and valid method to reflect exercise participation during home-based PR.