This study aimed to develop and implement an online inventory and monitoring system or medical supplies of the City Health Office (CHO) of Cagayan de Oro. Specifically, it aimed to provide the CHO with a system that allows all users to make supply – related transactions easily and speedily. The system also allows for an accurate tracking of inventory records. It creating an online inventory and monitoring system that uses PHP for the front-end, SQL Server for the back-end and Windows Server for the operating system. The new system provides the City Health Office with an efficient and convenient system for inventory of medical supplies of the CHO of Cagayan de Oro. The system generates accurate reports and facilitates transactions fast. Being efficient and convenient, the proposed system will improve the healthcare services of the City Health Office and that of barangay health centers.