For laboratories wishing to comply with the requirements of ISO 17025 quality management system, maintenance and improvement becomes two processes that are mutually inclusive. Like any other system, ISO 17025 system needs to be maintained through continual improvement. To effectively maintain ISO 17025 system through continual improvement in laboratories, certain critical success factors must be present. This study seeks to demonstrate the benefits for maintaining ISO 17025 system by identification of critical success factors for continual improvement of ISO 17025 system in a coal testing division. The study aims to highlight that through continual improvement of ISO 17025 system, organizations gain marketing edge and competitive advantage. The study process adopted a mixed method research by triangulation of quantitative and qualitative data. The research strategy used was a single case study by means of structured questionnaire. Convenience sampling method was adopted and 23 coal testing division employees participated in the study. The study highlighted that effective maintenance of ISO 17025 system through continual improvement may not necessarily guarantee error-free coal testing laboratories, but it will generate the needed confidence among coal end-users that the coal tested will satisfy coal quality requirements.