Cystopteris alpina is a fern in the family Cystopteridaceae. It is closely related to C. fragilis and has been treated as conspecific with that species by many authors. However, according to the Flora of North America, it is an allopolyploid species of hybrid origin, with Cystopteris montana as one probable parent. It is known to hybridise with C. fragilis in Scandinavia and intermediate plants possibly of hybrid origin are known from North Wales.