The aim of this study was to evaluate the use of a knee brace after arthroscopic anterior cruciate ligament reconstruction using central third patellar tendon autografts. Fifty patients were randomly allocated to two groups. The patients in Group A wore a brace for three weeks postoperatively, while the patients in Group B were rehabilitated without the use of a brace. Pre-operatively, the groups were comparable in terms of age, sex, activity level, knee laxity and muscle strength. The follow-up examination was performed by one independent observer. All the patients were followed up for a minimum of two years. At the follow-up, there were no significant differences between the study groups in terms of the Tegner activity level, Lysholm score, IKDC evaluation system, one-leg-hop quotient, KT-1000 measurements and isokinetic torque. Using the visual analogue scale, the patients in Group A evaluated their pain during the first two post-operative weeks as 1.0 (0-7), compared with 2.3 (0-9) in Group B (P= 0.04). Furthermore, the patients in Group A had a tendency towards fewer problems with swelling, haemathrosis and wound leakage during the early post-operative period (P=0.08). We conclude that the patients who were rehabilitated with the use of a brace had less pain and a tendency towards fewer complications during the early post-operative period than the patients who were rehabilitated without the use of a brace. However, there were no differences in terms of function or knee laxity at the two-year follow-up.