Background: Telehealth applications may improve health outcomes by engaging patients as active participants, focusing clinic visits on important problems and intensifying symptom management in response to patient reports. Our group developed an internet-based computerized system for patient self-report of symptoms (iComPAsS), and our aim is to evaluate the usability of this mobile application for reporting cancer symptoms among patient and physician end-users. Methods:The literature was surveyed for validated symptom tools available in both English and Filipino.A focused-group discussion (two oncologists, two pain specialists and an international symptom researcher) was conducted to assess face validity and elect an instrument. Application interface and system design was developed collaboratively with information technology consultants over several iterations until beta testing revealed a satisfactory design. Twenty end-users (10 physicians, 10 patients) were invited to assess the app's functionality after a training workshop. App assessment was done using the Mobile Application Rating Scale (MARS).Results: The Edmonton Symptom Assessment System (ESAS) was elected due to its validity, ease of administration and prevalent use in local research and clinical settings. The iComPAsS was shown to be satisfactorily functional on beta testing. It allows patients to report symptom severity, indicate pain location on a body diagram, view prescriptions, and receive notifications from their physicians. On usability testing, engagement, functionality, aesthetics and information scores revealed high and moderate acceptability among physician and patient users, respectively. A clinical trial will be conducted to determine its impact and define maintenance and scale-up issues. Conclusions:The iComPAsS mobile application for patient self-reporting of cancer symptoms is useable and acceptable by both physician and patient end-users.