This study presents the results of early rehabilitation approach in 57 patients treated with arthroscopic anterior cruciate ligament reconstruction due to chronic instability. The anterior cruciate ligament reconstruction was carried out with the Kenneth - Jones method utilising the proper patellar ligament autologous graft and interference screw fixation. After the surgery, patients were randomly assigned to two groups which were subject to identical three-month original proprietary rehabilitation programme, varying only by time of initiation. Group 1 started the rehabilitation process in the second postoperative day, whereas group 2 - in the third week after the surgery. The following criteria were established for comparison of the two study groups: knee joint range of motion, the presence of effusion within the joint by measurement of circumference of the knee and the number of knee aspirations carried out, pain, muscle wasting measured by circumference of the thigh and the muscle force of the flexors and extensors of the knee and stability of the knee. Obtained results confirmed the main thesis of research, that a delay of early rehabilitation by 2 weeks after arthroscopic anterior cruciate ligament reconstruction does not impair the final effect of rehabilitation treatment at 12 weeks after the surgery.