Lymphedema is a common complication associated with cancer itself or with cancer treatment. Lymphedema infrequently occurs after drug therapy. Bee venom is one of the materials used in acupuncture, and it has been used in the treatment of a variety of inflammatory diseases including arthritis. We report a 74-year-old male patient with late-onset post-radiation lymphedema provoked by bee venom therapy. He was free of lymphedema for 5 years after the complete remission of prostate cancer which had been treated with transurethral resection and radiation therapy. The patient developed left leg swelling after undergoing bee venom therapy for left hip pain. Computed tomography and lymphoscintigraphy showed lymphedema without tumor recurrence or infection. The lymphatic system was suspected to be injured by bee venom therapy and lymphedema was provoked. Bee venom therapy should be used cautiously in patients prone to lymphedema.