Abstract Infrared absorption was measured with five ω-hydroxy-1-alkenes in the 3 μ region, using an instrument of high resolution and the following results were obtained. 1) Intramolecular interaction between the hydroxyl group and π-electrons was found in allyl alcohol and in 3-buten-1-ol. 2) Interactions which occur in allyl alcohol and in 3-buten-1-ol may be of a different kind. 3) Higher homologs also possess two O–H stretching absorption bands but these bands can not be associated with the intramolecular interaction.