The Tokyo Women's Medical College library has a small AV-Room (20m2). This study analyzes the relationship between hours of utilization and the number of newly purchased video cassette tapes over 9 years from 1972 to 1980.Increase of utilization hours from 1974 to 1975 can be attributed to repletion of AV materials and convenience of use due to establishment of the AV-Room inside the library in August 1975. For the period 1975 to 1978 growth of utilization hours was parallel to increase in number video cassette tapes. In 1976 53 video cassette tapes were purchased, the most purchased in one year duringuthe period. Thereafter about 25 video cassette tapes were purchased annually through 1978.In 1979 utilization of the AV-Room began to slacken. This is because the purchase of new video cassette tapes was kept down to four, the lowest annual number. In 1979 the total number of video cassette tapes was 195 pieces, but addition of new cassettes diminished, causing reduction in hours of utilization.In order to increase the number of hours of utilization of the AV-Room, judging from the above, it is necessary to continuously purchase a variety of up-to-date video cassette tapes annually. At the same time, medical librarians shoud arrange AV materials for convenient use, publicize AV materials among instructors and students, and be ready to offer their services at any time.Average daily hours of utilization was 1 hour and 26 minutes, counting a month as 24 days. This means there is still much room for further utilization. Perhaps one should consider not only the number of video cassette tapes available, but also the service in supplying the materials by audio-visual material personnels.