The rotational spectrum of 1,4-anhydrothreitol (a C4 anhydrosugar) has been assigned by free jet millimeter wave spectroscopy. The structure, characterized by a distorted ring and one O-H center dot center dot center dot O hydrogen bond involving an alcoholic group and the ring oxygen, corresponds to the B3LYP/6-31G** global conformational minimum. Since C2 sugars have already been observed, and C3 sugars have been extensively searched in the interstellar medium (with controversial results) we propose 1,4-anhydrothreitol to be of interest for astrochemical observation. (C) 2008 Elsevier B.V. All rights reserved.