Background: Following the initial correction of a clubfoot using the Ponseti method, diminished passive ankle dorsiflexion may be observed over time, which could represent a possible relapsed deformity. Alternatively, the change may be attributable to patient age or other variables. Our purpose was to quantify passive ankle dorsiflexion in the involved and contralateral unaffected limbs of Ponseti-managed unilateral clubfoot patients, and to determine what patient-related variables influence this finding. Methods: In total, 132 unilateral clubfoot patients were studied. Passive ankle dorsiflexion was measured in both limbs at each visit. Data were excluded from visits in which patients showed clear evidence of a relapse. Mean ankle dorsiflexion for clubfeet and contralateral unaffected limbs were reported for annual age intervals and compared using paired t tests. A general linear model was established to assess the effects of age, severity, sex, and side on ankle dorsiflexion. Results: Mean ankle dorsiflexion for unaffected limbs declined with age, measuring 53±6 degrees between 0 and 1 year of age and decreasing to 39±7 degrees by 4 to 5 years of age. Similarly, mean ankle dorsiflexion in treated clubfeet declined with age, measuring 44±7 degrees between 0 and 1 year and 29±7 degrees between 4 and 5 years. Overall, the difference between limbs in these patients averaged ~10 degrees for every age interval through 9 years (P<0.001). Ankle dorsiflexion of clubfeet in 95% of patients aged 0 to 2 years was at least 20 degrees, and in 95% of patients aged 3 to 5 years this was at least 15 degrees. Patient age (P<0.001) and severity of deformity (P<0.001) were found to be the only significant factors affecting ankle dorsiflexion in the affected limbs. Conclusions: Ankle dorsiflexion in the Ponseti-treated clubfeet was influenced by age of the patient and the initial severity of the affected limb. Furthermore, our data suggest that, in patients who showed no relapse, a minimum of 20 degrees of ankle dorsiflexion in the corrected clubfoot is maintained through age 3 years and a minimum of 15 degrees is maintained through age 5 years. Level of Evidence: Level IV—this is a retrospective case series.