Alkaloids of Arundo donax L. growing in four soil-climatic regions of Uzbekistan were studied. The quantitative and qualitative compositions of alkaloids from native and introduced species were analyzed. Total bases were isolated by extracting air-dried material with ethanol/isopropanol and chloroform (after preliminary treatment with dilute ammonia), then separated and purified using column chromatography over Al₂O₃ and silica gel. Twenty alkaloids were isolated, including the new ones arundavine and arundafine, as well as a new type of dimeric indole alkaloids (arundamine, arundanine, and arundacine). The total alkaloids differed in quantity and composition between native and introduced species, with donaxine as the principal alkaloid of interest found mainly in the aerial part of introduced plants and the native plant from Fergana region. Native plants from Kashkadari and Fergana valleys were richer in alkaloids than introduced species and could serve as a source of donaxine.