We describe Clinical Trials System (CTS), an innovative EDC system utilizing data from existing hospital-based electronic databases that supports information gathering and storing for various clinical trials. The complexities of designing electronic clinical trials systems and their ideal features are outlined. CTS optimally utilizes existing electronic databases in a well-organized and easy-to-reference format. CTS is currently incorporated within a large psychiatric center, allowing easy sharing of information and data among multidisciplinary clinical and research teams.