BACKGROUND The aim of this paper is to present the physiotherapeutic program employed at the Rehabilitation Centre for the College of Physiotherapy in Wrocław, Poland and its effectiveness by demonstrating the increase in strength of knee joint extensor and flexor muscles of patients after anterior cruciate ligament (ACL) reconstruction. MATERIAL/METHODS Thirty-seven males participated in the physiotherapeutic program from the first week up to 8 months postoperatively. Each patient underwent an individual therapeutic program. Endoscopic reconstruction of a completely ruptured ACL was performed using Mitek's method (graft harvesting from flexor muscles). All patients previously underwent orthopedic and functional examinations, including measurements of the range of movement, knee and thigh circumference and strength of flexor and extensor muscles of the involved and uninvolved leg using a Biodex 3 System in both static and isokinetic modes. RESULTS The outcome of the physiotherapeutic procedure, which is detailed in the paper, revealed a favorable effect of physiotherapy 6 months after ACL reconstruction. The observed 9% deficit in extensor muscle strength measured under isokinetic conditions of the involved knees compared with the uninvolved knees led us to conclude that the period of physiotherapy should be extended beyond 6 months for some patients. CONCLUSIONS 1. Six months of physiotherapy following ACL reconstruction in males favorably affected muscle strength values of the involved and uninvolved knees under static and isokinetic conditions. 2. The application of individual loads during the sixth month of physiotherapy resulted in similar values of extensor and flexor muscle strength measured under static conditions, and flexor muscle strength measured under isokinetic conditions in involved and uninvolved knees.