Five indole compounds have been isolated from bovine pineal tissue and characterized as 5-methoxytryptophol, N-acetyl-5-methoxytryptamine (melatonin), 5-hydroxytryptophol, 5-methoxyindole-3-acetic acid, and 5-hydroxyindole-3-acetic acid. Pineal hydroxyindole-O-methyltransferase, with S-adenosylmethionine, converts 5-hydroxytryptophol to 5-methoxytryptophol.