Cordyceps, as a general term, describes a group of ascomycetous fungi growing on arthropods and other related fungi. Some cordyceps have been used in traditional Chinese medicine for centuries and cordyceps-derived products are currently a big industry in China. A number of medicinal and health products have been developed and extensively commercialized from natural Chinese cordyceps, its anamorphic fungus (Hirsutella sinensis), and other fungi known as Chinese cordyceps. The lack of a defined classification system for medicinal cordyceps fungi is a source of confusion in the industry and the public, and even among pharmaceutical scientists. This review summarizes the cordyceps fungi currently used in the industry in China with a special reference to clarify Chinese cordyceps and associated fungi. Cordyceps militaris, Cordyceps guangdongensis and Isaria cicadae are well recognized and commercialized cordyceps fungi in China. Except the natural Chinese cordyceps and its anamorphic fungus, Paecilomyces hepiali, Mortierella hepiali, Cephalosporium sinensis and Clonostachys rosea isolated from natural Chinese cordyceps are classified as Chinese cordyceps–associated fungi. P. hepiali is a cordyceps fungus based on current phylogenetic analysis of Hypocreales, while M. hepiali is a fungus in the Zygomycetes and should only be treated as associated fungus of Chinese cordyceps.
C. sinensis and C. rosea belong to the Hypocreales and their relationship to cordyceps fungi should be further studied. The exploitation of the resources of cordyceps fungi and their quality control in the industry should be major topics for future studies.