Portable medical devices have been playing an important role in improving health outcomes across the socio-economic spectrum. In the recent decades, substantial population have started using such devices to monitor important vital signs. Significant proportion of these users are older patients with chronic diseases, declined physical and/or cognitive capabilities. Furthermore, these portable devices are often used in unguided environments, that can present unpredictable use contexts. In this preliminary study, we conducted usability inspection on five portable medical devices. Cognitive walkthrough followed by Nielson’s ten Usability Heuristic evaluation method were utilized for the purpose of usability inspection. Sixteen usability concerns were uncovered in such evaluation study. We also recorded the elapsed time of measuring vital signs with all five devices on a daily basis in a month. The average total completion time after familiarization (after the first week) was 5.17 minutes. Results suggest that ‘non-expert’, independent users may face challenges when using portable medical devices in home care settings. Further, the study results also indicate that unsatisfactory usability of portable medical devices could pose hinderances in technology adoption among low eHealth literate users.