Objectives. To determine whether ankle range of motion during ergometer rowing is best approximated by reliable active or passive plantarflexion and dorsiflexion tests.Design. Repeated measures and cross-sectional.Setting. In a laboratory setting, an electrogoniometer was attached to each subjects' left ankle during active, passive and dynamic ankle range of motion tests.Participants. Three adult males and seven adult females participated in part A of the study. Ten junior male rowers took part in Part B of the study.Main outcome measures. Endpoint plantarflexion and dorsiflexion.Results. Mean active and passive endpoint plantarflexion were significantly greater than mean plantarflexion achieved during ergometer rowing. In comparison, endpoint dorsiflexion measured passively and during ergometer rowing were not significantly different (P=0.40), and moderately correlated (r=0.60, 95% CI=-0.05-0.89). The active and passive ankle range of motion tests were reliable (r=0.90-0.95, highest SEM=2.8 o , 95% CI=1.9-5.1 o ). The passive tests produced significantly greater mean endpoint ankle plantarflexion (7.4 o +/-3.7 o , 14.9%) and dorsiflexion (6.5 o +/-3.7 o , 28.2%) than the active tests.Conclusions. Compared to dynamic measurement, passive plantarflexion and dorsiflexion are the preferred tests to assess rowers' ankle motion due to the high reliability, validity and easier measurement procedures.