Background: Range of motion exercise is a key component of burn therapy across all phases of care. Aim: Assess the effect of range of motion exercise program on joints function of burned lower limbs Patients. Research design: A quasi experimental (pre / post- test) research design was used. Setting: The study was conducted in burn unit at Al Shamla Hospital, Al Mabara Hospital and Al Eman Hospital. Sample: Purposive thirty adult patients (male and female) admitted to burn units. Tools: Patient's assessment sheet, joints function assessment (pre, post). Results; There was a statistical significance difference as regard patient range of motion on lower limb joints pre-post program implementation (p < 0.005). Conclusion: lower limb joints function was improved among patients who received range of motion exercise program. Recommendation: Simple instructions hand book illustrating necessary information and range of motion exercise program should be available for lower limb burned patients and nurses working in burn unit.