Background. Thirty two male patients with the full-thickness lesion of articular cartilage on the load-bearing surface of the knee joint (Outerbridge Grade III-IV) were involved in the study. The goal of this paper is the biomechanical assessment of changes in the kinematics of gait of patients after selected articular cartilage surgeries of knee joint examined by the 3D motion analysis system (SIMI Reality Motion Systems GmbH, Germany). Material and methods. Gait of thirty two patients with the articular cartilage surgery of knee joint was analyzed while they underwent 2 out of 4 stages of our original physiotherapy treatment. In order to test the progress of the rehabilitation program the spatial kinematic data of the gait was collected and the angle-time characteristics acquired. The first measurement was taken between the 2nd and 3rd week postoperatively, the second was taken between 6th and 8th week postop. The last measurement was taken between 10th and 14th week postoperatively, when the patient’s gait was fully restored and being improved. The values of step and stride lengths (meters), gait velocity (meters per sec.) and the step cadence (steps per sec.) were monitored as well as the stance and swing ratios (percent of the gait cycle) of the affected and unaffected limb. Range of motion in the knee joint was examined in dynamics and the angles at heel-strike and toe-off measured for both lower limbs. Results. As a consequence of our rehabilitation procedure satisfactory results were obtained individually between 10th and 14th week postop. in test patients with reference to the control group. The spatial gait parameters step and stride lengths have significantly increased and the stance to swing ratio have decreased for the affected limb compared to the first measurement. The gait velocity was found to be doubled. In addition an increase in range of motion in the joints was noticed and the angle characteristics was similar to the one of the control group. Conclusions. The extensive surgical and physiotherapeutic procedures applied in the treatment have improved gait parameters between 10th and 14th week postop in all tested patients.