Objectives: This study aimed to compose a formula to predict the Hemophilic Joint Health Score (HJHS) for hemophilia patientsin West Java, find out the validity of the prediction formula and identify the difference between observational HJHS and predicted HJHS. Methods: This observational, cross-sectional study involved hemophilia patients that were registered with the Indonesian Society of Hemophilia Patient in West Java aged 4-18 years old with all stages of severity. All participants were assessed with the observational HJHS using HJHS version 2.1. Regression analysis between age and disease severity was done to compose a prediction formula. Residual analysis was performed to determine the validity of HJHS prediction formula. The HJHS of all participants was calculated with the prediction formula and mean of observational HJHS and predicted score was compared. Results: Regression analysis yielded HJHS predictionformulabasedonageandseverityofdisease,is:TotalHJHS=-7.57+ 0.952 x AGE + 2.369 x DISEASE SEVERITY (age in years, disease severity, mild =1, moderate = 2 and severe = 3). This HJHS prediction formula is valid because mean of residual analysis is 0, with normal data distribution. Comparison of the mean of observational HJHS and prediction HJHS did not show any significant difference (p=0.51). Conclusion: The prediction formula obtained in this study is valid and can be applied to hemophilic patients in West Java. The HJHS calculated with prediction formula does nothave significant difference compared to the observational HJHS.