冬虫夏草（学名：Cordyceps sinensis (Berk.) Sacc.），是中国历史中传统的名贵中药材，是由肉座菌目麦角菌科麦角菌属的冬虫夏草菌寄生于高山草甸土中的蝠蛾幼虫，使幼虫身躯僵化。并在适宜条件下，夏季由僵虫头端抽生出长棒状的子座而形成，即冬虫夏草菌的子实体与僵虫菌核（幼虫尸体）构成的复合体。目前主要认为冬虫夏草的真菌无性型为中国被毛孢（学名：Hisutella sinensis）。冬虫夏草主要产于中国大陆青海、**、四川、云南、甘肃、贵州等省及自治区的高寒地带和雪山草原。

冬虫夏草「补肺益肾，止血化痰，秘精益气」。

Ophiocordyceps sinensis is a fungus that parasitizes larvae of ghost moths and produces a fruiting body valued as an herbal remedy found in mountainous regions of India, Nepal and *****.

The fungus germinates in the living larva, kills and mummifies it, and then the stalk-like fruiting body emerges from the corpse. It is known in English colloquially as caterpillar fungus, or by its more prominent names Yartsa Gunbu (*****: དབྱར་རྩྭ་དགུན་འབུ་, Wylie: dbyar rtswa dgun 'bu, literally "winter worm, summer grass"), or Dōng chóng xià cǎo (Chinese:冬虫夏草). Of the various entomopathogenic fungi, Ophiocordyceps sinensis is one that has been used for at least 2000 years for its reputed abilities to treat many diseases related to lungs, kidney, and erectile dysfunction. This fungus is not yet cultivated commercially, despite the fact that several fermentable strains of Ophiocordyceps sinensis have been isolated by Chinese scientists. Overharvesting and overexploitation have led to the classification of O. sinensis as an endangered species in China. Additional research needs to be carried out in order to understand its morphology and growth habits for conservation and optimum utilization.