The validity of intraoperative frozen section diagnosis (IFSD) via telepathology between Hokkaido University School of Medicine (HUSM) and a remote hospital was evaluated. Video-microscopic images of hematoxylin-eosin (HE)-stained frozen sections were transmitted by a cytoscreener via the Pathtran 1,000 system and a telephone line to a color monitor at HUSM (120 km from the submitting hospital) with a resolution of 512 x 480 pixel matrix. The pathologists at HUSM made diagnoses on the received images. Of the 59 cases, there was diagnostic concordance between telepathology and permanent paraffin sections in 19 malignant, 36 benign, and one borderline case. The latter was a case of atypical ductal hyperplasia of the breast. The telepathology diagnostic modality was inconclusive in three cases, two of which were benign and one malignant by paraffin section examination. These results provide evidence for the diagnostic adequacy of video-microscopic images, the interpretation of which compared favorably with that of conventional frozen sections. Although the need for IFSD is increasing, the proportion of hospital pathologists accepting this modality is not. For the appropriate use of telepathology, it is necessary that more pertinent personnel, especially cytoscreeners and pathologists receive a thorough training and become familiar with the system. Telepathology offers pathologists a diagnostic modality that responds to the needs of physicians and serves to enhance the pathologist's position in health care services.