The study was conducted to determine the influence of quality management system (QMS) and organizational culture on the performance of San Pedro Hospital (SPH). QMS refers to the objectives, policies, procedures, plans, resources, and processes of the organization, and delineation of responsibility and authority, with the purpose of achieving product or service quality levels with customer satisfaction as the focus. Descriptive-correlation method was used in the study, employing the 65 rank and file regular employees from the years 2000 to 2006 as participants for the internal customers. Data were gathered using a researcher-made questionnaire, validated, and pre-tested. Statistical tools employed were frequencies and percentages, weighted mean and standard deviation, Pearson r, and t test. The result of the study shows that the requirements of International Organization for Standardization (ISO) certified QMS are considered, followed, and implemented. Likewise, the statistical data illustrates that the QMS has an influence on the improvement of the performance of SPH from average, to a high level in areas of efficiency, output, and customer satisfaction; that the organizational culture influences the QMS, that is, the former provides a healthy environment for the latter to function efficiently and effectively. It is therefore recommended that SPH should maintain the ISO certification status. Furthermore, the institution should continue to cherish, promote, enhance, and nurture the identified noble and wholesome culture as well as explore the possibilities of empowering the employees. Finally, communication processes need to be improved, particularly in the aspect of consulting people regarding work and responsibilities.