INTRODUCTION: Thymoma is a rare tumor for which there is little randomized evidence to guide treatment. Because of the lack of high-quality evidence, a formal consensus-based approach was used to develop recommendations on treatment. METHODS: A systematic refview of the literature was performed. Recommendations were formed from available evidence and developed through a two-round modified Delphi consensus approach. RESULTS: The treatment recommendations are summarized as follows: Stage I--complete resection of the entire thymus without neoadjuvant or adjuvant therapy. Stage II--complete resection of the entire thymus with consideration of adjuvant radiation for high-risk tumors. Stage IIIA--surgery either initially or after neoadjuvant therapy, or surgery followed by adjuvant therapy. Stage IIIB--treatment may include a combination of chemotherapy, radiation, and/or surgery, or if technically possible, surgery in combination with chemoradiotherapy (concurrent cisplatin based). For bulky tumors, consideration should be given to sequential chemotherapy followed by radiation. Stage IVA--as per stage III, with surgery only if metastases can be resected. Stage IVB--treatment on an individual case basis (no generic recommendations). Recurrent disease--consider surgery, radiation, and/or chemoradiation. Chemoradiation should be considered in all medically inoperable and technically inoperable patients. CONCLUSION: Consensus was achieved on these recommendations, which serve to provide practical guidance to the physician treating this rare disease.