Five dihaloacetamides, seven halogenated but-3-en-2-ols, and twenty halogenated isopropanols have been identified in the methylene chloride extract of the dried red alga Asparagopsis taxiformis from Hawaii. The structures of 1, 1, 4, 4-tetrabromobut-3-en-2-ol and 1, 1, 1, 4, 4-pentabromobut-3-en-2-ol have been verified by synthesis.