After a strict filtering process, the papers were examined for data pertaining to the biochemistry, distribution, ecology, genomic information, host range, infection biol- ogy, morphology and phylogeny of the species. The results reveal that there is a large amount of ambiguous and sometimes spurious citation of G. fusipes in the literature. However, it can be confirmed that G. fusipes is a facultative saproparasite, found in several countries, mainly in Europe, and is associated with several socioeconomically important host species, including oak, chestnut, and fir. Gymnopus fusipes has repeat- edly been investigated with regard to oak decline in Europe, where it is believed to play a crucial role in the early stage of decline development. Key knowledge gaps highlighted in this review include a lack of information on the basic biology of the spe- cies, including its life cycle, which is crucial to fully understanding G. fusipes infection and epidemiology. Further work is needed to assess G. fusipes distribution, phylogeny and host range through molecular identification. There is also a need to character- ize the pathogen– host interaction at a molecular level, with identification of active genes and therefore the mechanisms of infection. A combination of culture- based and molecular techniques should be utilized in order to close these key knowledge gaps.