OBJECTIVE The purpose of this prospective clinical study was to evaluate the outcome of periradicular surgery of molars after one year. METHODS The material consisted of 25 molars with 39 roots demonstrating periradicular lesions of endodontic origin. Surgical treatment included root-end resection, root-end preparation with sonic microtips, and root-end filling with Super-EBA cement. At the one-year follow-up examination, healing was evaluated clinically and radiographically. Healing was assigned to three categories: (i) success (ii) improvement, and (iii) failure using well defined criteria. RESULTS Eighty-eight per cent of the surgically treated molars showed successful healing. In 8%, the healing was rated as improved and only 4% were failures. CONCLUSIONS The outcome of the present study and data of recently published studies show that periradicular surgery may result in a predictable treatment outcome in molars with persistent periradicular lesions.