Objective:To determine the minimum clinically-important difference (MCID) in the rehabilitation effect among children with haemophilic knee joint contracture.Methods:The data describing 28 children with an average age of 13.89±3.00 years and haemophilic knee joint contracture who received no less than 10 sessions of physiotherapy in the Department of Rehabilitation Medicine at the Peking Union Medical College Hospital were analyzed. The therapeutic effect of the treatement was quantified in terms of Haemophilia Joint Health Scores (HJHSs) for their knees. The MCID after the therapy was evaluated using the mean change method, multivariate linear regression, receiver operating characteristics, and the distribution-based method.Results:The MCID for the improvement of knee HJHS was 5.13 by the mean change method, 4.31 by multivariate linear regression, 3.50 according to the ROC curve and 1.64 by the distribution-based method. Taking all of them into consideration, 4.31 was found to be an appropriate value.Conclusions:The MCID after physical therapy for the improvement in knee HJHS for a child with haemophilic knee contracture is 4.31. Improvements greater than 4.31 can be considered clinically significant.