The structures of a number of compounds isolated from the stems of Tinospora smilacina (known as ‘snakevine’) have been determined. The known clerodane-type compound columbin is a major component, and two new minor compounds incorporate a heavily oxygenated tetrahydrofuran ring in place of the furan ring of columbin. The lignan isolariciresinol is also shown to be a minor component, along with dihydrosyringenin. The traditional medicinal use of the vine, particularly in countering snake venom, may be associated primarily with the presence of columbin.