In this study an autologous graft of 50%-60% of the patellar tendon (mid portion) was used for anterior cruciate ligament (ACL) reconstruction in 50 patients (19 women, 31 men; mean age 26 years). The distal part of the graft was fixed in a tunnel running from the centre of the anatomical tibial attachment of the ACL to the place where the bone block of the graft was removed from the tibial tubercle. A rehabilitation programme with accelerated weight-bearing postoperatively without external protection was followed. Evaluation consisting of function and stability tests, activity level and Lysholm's subjective function score took place an average of 26 months postoperatively; 35 of 50 patients had an additional evaluation monthly for 1 year and 6 monthly after 1 year. The stability tested manually after an average of 26 months postoperatively was good in 45 patients; 5 of them had a positive Pivot shift test (one 1+, two 2+, two 3+). Only 2 of these patients complained of giving way of the knee. All patients regained good knee function. The average postoperative Lysholm score was 85 (SD 14.5) and the subjective stability of the knee was described as 'good' in 41 patients, and 'poor' in 9. The objective stability was good in 7 of these 9 patients. The mean Tegner score was 6.5 (SD 1.9). The mean time to resuming activities was 5.4 weeks for full weight-bearing, 10 weeks for running, 13.5 weeks for going back to work and 6 months for returning to previous sports. In the group of 35 patients who underwent an additional evaluation, no change in manual stability was found during observation except for 3 of them. No patellar ruptures were seen. The operation technique used in this study appears to allow accelerated knee rehabilitation after ACL reconstruction.