Telemedicine is becoming widely used in healthcare. Dermatology, because of its visual character, is especially suitable for telemedicine applications. Most common is teledermatology between general practitioners and dermatologists (secondary teledermatology). Another form of the teledermatology process is communication among dermatologists (tertiary teledermatology). The objective of this systematic review is to give an overview of studies on tertiary teledermatology with emphasis on the categories of use. A systematic literature search on tertiary teledermatology studies used all databases of the Cochrane Library, MEDLINE (1966-November 2007) and EMBASE (1980-November 2007). Categories of use were identified for all included articles and the modalities of tertiary teledermatology were extracted, together with technology, the setting the outcome measures, and their results. The search resulted in 1,377 publications, of which 11 were included. Four categories of use were found: getting an expert opinion from a specialized, often academic dermatologist (6/11); resident training (2/11); continuing medical education (4/11); and second opinion from a nonspecialized dermatologist (2/11). Three modalities were found: a teledermatology consultation application (7/11), a Web site (2/11), and an e-mail list (1/11). The majority (7/11) used store-and-forward, and 3/11 used store-and-forward and real-time. Outcome measures mentioned were learning effect (6), costs (5), diagnostic accuracy (1), validity (2) and reliability (2), patient and physician satisfaction (1), and efficiency improvement (3). Tertiary teledermatology's main category of use is getting an expert opinion from a specialized, often academic dermatologist. Tertiary teledermatology research is still in early development. Future research should focus on identifying the scale of tertiary teledermatology and on what modality of teledermatology is most suited for what purpose in communication among dermatologists.