The availability of timely and accurate data is vital to make informed medical decisions. Today patients data required to make informed medical decisions are trapped within fragmented and disparate clinical and administrative systems that are not properly integrated or fully utilized. Therefore, there is a growing need in the healthcare sector to store and organize size-able clinical record of patients to assist the healthcare professionals in decision making processes. This research is about integrating and organizing disparate clinical record of patients into a Data Warehouse (DW) for data analysis and mining, which will enable evidence-based decision-making processes. This study uses SQL Server Integration Service (SSIS) for the extraction transformation and loading (ETL) of patient clinical records from fragmented administrative systems into the DW, Data visualization technique was used for data presentation while SQL Server Reporting Services and Business Intelligent (BI) tools for designing the output results. This research will assist medical experts and decision makers in the healthcare industry in planning for the future. This research also provides an architecture for designing a clinical DW that is not limited to single disease and will operate as a distributed system, Periodic update on a daily basis is possible because contemporary technologies have narrowed the gap between updates which enable organizations to have a “real time” DW which can be analyzed using an OLAP Server. In conclusion if this research is deployed it will aid medical decision-making process in the Nigerian medical sector.