Background and aim:  For the rehabilitation program of the anterior cruciate ligament reconstructed patients (ACLR) strength and functional assessment and comparing with the uninvolved side is in great importance. Strength plays an important role in performing vertical jump moreover. It is performed in closed kinetic chain. Despite this importance, no information exists regarding the relationship on peak force of linear isokinetic and vertical jump score. The purposes of this study were1- To determine correlation between isokinetic squat and vertical jump in healthy and ACLR patients. 2- Comparing the peak force and vertical jump between the involved and uninvolved side of the ACLR patients.   
Materials and Methods: Twenty two ACLR patients with 6 months post-surgery and 16 healthy men participated in this study. Their isokinetic squat strength at the testing velocity of 25.4 cm/sec and vertical jump was measured.
Results: ACLR patients' peak force and vertical jump were significantly different between the involved and uninvolved side P≤0.05. The findings showed low relationship )r=0.425)  at the involved side between the vertical jump and peak force of squat, however, there was no relationship in the uninvolved side and the control group.
Conclusion: Findings of  this study indicate no relationship between vertical jump and peak force of squat. Both testing methods should be used since strength not always correlate strongly with physical performance.   Closed kinetic chain isokinetic testing should be used for testing lower extremity strength, while vertical jump should be used to determine performance levels.