Introduction: Chronic mechanical low back pain (CMLBP) is the most common complaint of the working-age population. In addition to human suffering, it causes a substantial economic burden due to the wide use of medical services and absence from work. Imbalance between hip internal and external rotators muscles may be a contributing factor for low back pain. Aim of Work: To assess the relationship between hip internal and external rotators strength in patients with chronic low back pain (CLBP). Materials and Methods: Patients with CLBP was referred to outpatient clinic, faculty of Physical Therapy Cairo University. Sixty patients (53 male and 7 females) suffering from CLBP their age ranged from 20-30 years with mean of age (23.76±2.39) years. We assess hip rotators (internal and external) strength by using isokinetic dynamometer concentric contraction protocol. We select two speeds to assess muscle strength (60˚ ∕ sec as low speed and 180˚ ∕ sec as high speed). Peak torque is the reading we select to resemble muscle strength. Results: in both sides paired –t test revealed that there is significant different between hip internal rotators peak torque and peak torque of hip external rotators in low speed concentric torque , also at high speed concentric torque(p<0.05) . Conclusion: in patient with CLBP there is imbalance between hip rotators, hip internal rotators muscles is stronger than external rotators muscles.