BACKGROUND: Orthopedic physicians typically apply a cast to immobilize a body part that has been injured. There have been no significant structural changes or advances in synthetic casts since the development of the modern cast. The Opencast® is a recently developed type of cast that allows ventilation and direct visual inspection of the skin to avoid cast-related complications. Although this novel cast appears to have more benefits than the conventional synthetic cast, its clinical efficacy and advantages have not been established. AIM: To investigate the clinical efficacy and advantages of the newly developed Opencast® based on patients' perspectives in those with ankle inversion injury. METHODS: A specifically designed questionnaire consisting of 19 items was used to compare patients' opinions and concerns of the Opencast® and the conventional synthetic cast. The items were focused on subjective patient satisfaction, discomfort, and adverse effects while wearing the cast. Patients with an ankle inversion injury diagnosed as a high-grade ankle sprain were enrolled. The subjects were randomized and instructed to fill the questionnaire after wearing a synthetic cast or an Opencast® for 2 wk. They were then required to fill the questionnaire again, after switching to the alternative type of cast for 2 more weeks. RESULTS: A total of 22 subjects participated in the study. The synthetic cast appeared to be more rigid and stable than the Opencast®, but there was no significant difference in the amount of pain relief. The likelihood of adverse effects when wearing the synthetic cast was significantly higher. Patient satisfaction tended to be rated higher after wearing the Opencast®. Opencast® showed more subjective vulnerability than the synthetic cast, but there was no significant difference in the redo rate. Patients were more anxious about removal of the synthetic cast than of the Opencast®. CONCLUSION: The results indicate that the Opencast® could replace the conventional synthetic cast as it offers increased patient satisfaction, which would in turn increase compliance to treatment.