PURPOSE: this study was conducted to assess the safety and efficacy of a new surgical technique for anatomical reconstruction of the coracoclavicular (CC) and acromioclavicular (AC) ligaments using one single-strand semitendinosus tendon graft. METHODS: eighteen patients affected by chronic type III-V AC joint dislocations were included in the present study between January 2010 and March 2012. All underwent the same surgical operation and rehabilitation protocol. The semitendinosus tendon was harvested from the ipsilateral knee. The CC and AC ligaments were reconstructed using the graft passed beneath the coracoid and through bone tunnels in the clavicle and in the acromion. The graft was secured with non-absorbable sutures. Radiographic recurrence of AC joint dislocation was the primary outcome. Clinical outcome was assessed using the DASH score and normalized Constant score. Wilcoxon's signed-rank test was used for comparison between pre- and postoperative results. Significance was set at p ≤ 0.05. RESULTS: the mean follow-up duration was 26.4±2.3 months (range: 24-30 months). On X-ray evaluation, only two patients (11%) showed asymptomatic recurrence of AC joint instability. Comparison between pre- and postoperative DASH and Constant scores showed significant clinical improvement (p<0.001). CONCLUSION: anatomical reconstruction of CC and AC ligaments using an autologous semitendinosus tendon graft for the treatment of AC joint dislocation provided good and reliable clinical and radiological results with a low failure rate at short-term follow-up. LEVEL OF EVIDENCE: level IV, therapeutic case series.