It has been demonstrated that electronic patient registries combined with a clinical decision support system have a significant positive impact on the documentation and delivery of services provided by health care professionals. While implementation of available commercial systems has not always been proven effective in a number of primary care practices, development and implementation of such a system in a practice-based research network might enhance successful implementation. Physicians in our practice-based research network (Oklahoma Physicians Resource/Research Network) initiated a project that aimed at designing, testing, and implementing a personal digital assistant-based diabetes management system. We utilized the "best practice" approach to determine the principles on which the application must operate. System development and beta testing were also accomplished based on the direct feedback of user clinicians. Practice Enhancement Assistants (PEAs) were available in the practices for assistance with implementation. Implementation of the Diabetes Patient Tracker (DPT) resulted in a significant improvement (p<0.05) in nine of 10 diabetic quality of care measures compared with pre-intervention levels in 20 primary care practices. Regular PEA visits similarly increased the number of foot exams and retinal exams performed in the last year (p=0.03 and 0.02, respectively). DPT is a low-cost, feasible, easily implementable, and very effective paper-less tool that significantly improves patient care and documentation in primary care practices.