This paper describes the development and implementation of the first phase of a comprehensive clinical information system in the Kaiser Permanente Northwest Region. This system integrates information from disparate departmental systems into a single clinical database. By using periodic batch downloads of patient data from departmental systems into the clinical database, rather than requiring real-time updates, we have been able to implement this system with relative ease and speed. It contains patient demographics, lab, outpatient pharmacy, radiology, pathology, dictated consults, admission histories and physicals, discharge summaries, and other dictated reports for over 380,000 Health Plan Members. The system is fast, intuitive, reliable, and user-friendly. In March 1994, there were approximately 1,600 active users. These individuals accounted for approximately 410,000 transactions in the month, with an average daily transaction volume of 11,450. Quantifiable cost-savings, in terms of decreased chart pulls and decreased phone calls for information, have offset the cost of development and implementation to some extent. Less quantifiable improvements in the quality of care and the associated cost-savings may eclipse the quantifiable benefits. This system lays the foundation for our clinical information system efforts.