PURPOSE: The purpose of this article is to show the efficacy of a biodegradable plate for treating lateral malleolar fractures in the ankle joint. MATERIALS AND METHODS: The 20 patients who underwent an open reduction and internal fixation for lateral malleolar fractures in the ankle joint from February, 2006 to February, 2007 in our hospital were enrolled into the study. The average age of the patients was 49.7 years and the average follow-up period was 5.6 months. The cases were analyzed by radiological bone union time and clinical results according to the criteria of Meyer et al. RESULTS: Average radiological bone union time was 10.5 weeks. The clinical result was excellent in 19 cases (95%), good in 1 case (5%). There was one case of minimal displacement less than 1 mm, associated with anterior distal tibio-fibular ligament avulsion fracture. CONCLUSION: For proper patients, a biodegradable plate is an effecttive alternative implant for stabilizing lateral malleolar fractures in the ankle joint, because there is no requirement for subsequent removal and slow resorption in vivo.