The advent of smartphones has enabled a plethora of medical apps for disease management. As of 2012, there are 40,000 health care-related mobile apps available in the market. Since most of these medical apps do not go through any stringent quality assessment, there is a risk of consumers being misinformed or misled by unreliable information. In this regard, apps that target medication-related problems (MRPs) are not an exception. There is little information on what constitutes quality in apps that target MRPs and how good the existing apps are.To develop a quality assessment tool for evaluating apps that target MRPs and assess the quality of such apps available in the major mobile app stores (iTunes and Google Play).The top 100 free and paid apps in the medical categories of iTunes and Google Play stores (total of 400 apps) were screened for inclusion in the final analysis. English language apps that targeted MRPs were downloaded on test devices to evaluate their quality. Apps intended for clinicians, patients, or both were eligible for evaluation. The quality assessment tool consisted of 4 sections (appropriateness, reliability, usability, privacy), which determined the overall quality of the apps. Apps that fulfilled the inclusion criteria were classified based on the presence of any 1 or more of the 5 features considered important for apps targeting MRPs (monitoring, interaction checker, dose calculator, medication information, medication record). Descriptive statistics and Mann-Whitney tests were used for analysis.Final analysis was based on 59 apps that fulfilled the study inclusion criteria. Apps with interaction checker (66.9%) and monitoring features (54.8%) had the highest and lowest overall qualities. Paid apps generally scored higher for usability than free apps (P = 0.006) but lower for privacy (P = 0.003). Half of the interaction checker apps were unable to detect interactions with herbal medications. Blood pressure and heart rate monitoring apps had the highest overall quality scores (67.7%), while apps that monitored visual, hearing, and temperature changes scored the lowest (35.5%).A quality assessment tool for evaluating medical apps targeting MRPs has been developed. Clinicians can use this tool to guide their assessments of medical apps that are appropriate for use in the health care setting. Although potentially useful apps were identified, many apps were found to have deficiencies in quality, among which was poor reliability scores for most of the apps. Continued assessments of the quality of apps targeting MRPs are recommended to ensure their usefulness for clinicians and patients.No outside funding supported this study. The authors have no conflicts of interests directly related to this study. Study concept and design were contributed by Loy and Yap. Loy collected the data and took the lead in data interpretation, along with Ali and Yap. The manuscript was primarily written by Loy, along with Yap, and revised primarily by Ali, along with Yap.