Amantadine (trade name Symmetrel, by Endo Pharmaceuticals) is a drug that has US Food and Drug Administration approval for use both as an antiviral and an antiparkinsonian drug. It is the organic compound 1-adamantylamine or 1-aminoadamantane, meaning it consists of an adamantane backbone that has an amino group substituted at one of the four methyne positions. Rimantadine is a closely related derivative of adamantane with similar biological properties.

Apart from medical uses, this compound is useful as a building block, allowing the insertion of an adamantyl group.

According to the US Centers for Disease Control and Prevention, 100% of seasonal H3N2 and 2009 pandemic flu samples tested have shown resistance to adamantanes, and amantadine is no longer recommended for treatment of influenza. Additionally, its effectiveness as an antiparkinsonian drug is controversial, with a 2003 Cochrane Review concluding that it was ineffective for this purpose.

Amantadine was approved by the U.S. Food and Drug Administration in October 1966 as a prophylactic agent against Asian influenza and eventually received approval for the treatment of Influenzavirus A in adults. In 1969, the drug was also discovered by accident to help reduce symptoms of Parkinson's disease, drug-induced extrapyramidal syndromes and akathisia.