The effectiveness of a hospital information system (HIS) and a radiological information system (RIS) was evaluated to optimize preparation for the planned full clinical operation of a picture archiving and communication system (PACS), which is now linked experimentally to the HIS and the RIS. One thousand IC (integrated circuit) cards were used for time studies and flow studies in the hospital. Measurements were performed on image examination order entry, image examination, reporting, and image delivery times. Even though after the HIS and the RIS operation only a smatl amount of time savings were realized in each time fraction component, such as in the patient movement time, examination time, and film delivery time, the total turn-around time was shortened markedly, by more than 23 hours on average. It was verified that the HIS and the RIS was beneficial in the outpatient clinics of the orthopedic department. Our method of measurement employing IC cards before and after HIS and RIS operations can be applied in other hospitals. Copyright 9 1997 by W.B. Saunders Company KEY WORDS: technology assessment, picture archiving and communication system (PACS), radiological information system (RISI, hospital information system (HIS), radiological reporting, computers, radiology.T O SUCCESSFULLY operate the picture archiving and communication system (PACS) in a hospital radiology practice, it is indispensable to establish routine operation of the systems supporting the PACS, such as the hospital information system (HIS) and radiological information system (R[S). In the Osaka University Hospital, HIS and RIS have been in clinical operation since October t993.Several experimental PACS units have been installed and their clinical operation attempted since 1986; this provided opportunities for improvement to be found and realized.l-3 The final version of the experimental PACS was introduced into the hospital in October of 1996 and linked to the existing HIS and RIS. A quantitative evaluation of the PACS will be performed. The effectiveness of the HIS and the RIS evaluated by quantitative studies before and after the separate introduction of the HIS and of the RISas reported in this paper will permit us to measure the impact of the PACS alone.Many papers have been published regarding this issue, 4-~ but concrete data and results of measurement acquired using a rigorous method of comparison such as that presented here have not yet been published.It is also clear that the effect of the HIS and the RIS on radiological practice should be assessed and compared along with the effect on other departments. The analysis of the measurement results should be employed to optimize the design and future development of PACS as well as the HIS and the RIS.Finally, the methodology of generating quantitative data for the same target processes should be standardized so that the same evaluation can be conducted in other hospitals following the same method.