As the number of older adults who are using the internet increases, there is a need to consider accessibility in mobile application design. Web accessibility means that users of all groups should be able to access information easily. Telemedicine systems are now widely available, including in Indonesia. Older adults are among the user groups for which a telemedicine system is targeted. The question is whether and how far has the current telemedicine system has addressed accessibility in its application design. Halodoc is a well-known telemedicine system in Indonesia. In this research, we tested Halodoc mobile application's accessibility using two methods: scanner test using Accessibility Scanner tool and user test. From the scanner test, many accessibility issues are found, such as small touch targets, insufficient text, and poor image contrasts. From the user tests, we observed that users needed more than two minutes to finish a task. We also found that the accessibility issues were caused not only by non-compliance with WCAG 2.0 guidelines but also by the user interface design. © 2021 IEEE.