Telepathology is the practice of diagnostic histopathology performed on digital pictures. In this study, we focused on the technical requirements for achievement of a correct diagnosis on digital histopathologic images. A collection of 560 melanocytic lesions was selected from the files of the Department of Dermatology, Medical University of Graz, Austria. From each lesion one histologic slide was completely digitally scanned with a robotic microscope. Digital pictures were reviewed by 4 dermatopathologists using a presentation program, which recorded the number of image calls, applied magnifications, overall time needed, and amount of transmitted bits during the digital sign-out. One month later, the 4 microscopists had to review the corresponding slides and render a direct diagnosis on each case. Telepathologic diagnoses corresponded with the original diagnoses in a range from 90.4% to 96.4% of cases (kappa 0.80 to 0.93; P < 0.001). The median time needed for achievement of a diagnosis was 22 seconds and was significantly higher for melanomas compared with nevi. The median transmission effort for each diagnosis was 510 kilobytes after JPEG compression. Using an ISDN line with a transmission capacity of 64 kilobits/ second, this correlates to a transmission time of about 1 minute. Our results demonstrate that correct reporting on digital histopathologic images is possible with only a little time exposure. For an adequately fast transmission ISDN lines are suffcient after JPEG compression.