Of the multitude of products obtained upon the aqueous chlorination of α-terpineol ( 1), under both acidic and basic conditions, the major ones are the diequatorial trans, 4, and diaxial trans, 5, Markovnikov adducts of hypochlorous acid to the olefinic center. With the exclusion of small amounts of dichloride formation, the remainder of the products appear to be derived from 4 and 5 by hydrolysis or elimination sequences. The product distribution exhibits an expected pH dependence that is useful in the structural assignments.