The intermolecular complexes of furan with hydrogen halides are examined using ab initio calculations performed at the second-order Moller-Plesset perturbation approximation with the 6-311++G(d,p) basis set. Two types of geometry are observed: the atom-on geometry, featuring a roughly planar complex with C-2v symmetry and a hydrogen bond between the furan oxygen and the hydrogen halide; and the face-on geometry, in which the hydrogen halide lies above the furan ring in an orientation almost perpendicular to the plane of the ring. The furan-HF and furan-HI complexes are each found to have one minimum geometry, of the atom-on and face-on type, respectively. Both geometry types are obtained for the HCl- and HBr-furan complexes. With the exception of furan-HCl, the HX subunits of the atom-on complexes deviate slightly from the furan ring plane. Each of the face-on complexes shows interaction between the hydrogen of the halide subunit and the formal pi-bond between C-2 and C-4 of the furan ring. An electrostatic density potential map of furan was generated for the determination of attractive interaction sites. Interaction energy decomposition reveals that atom-on complex interactions are predominantly electrostatic in nature, while orbital and electrostatic interactions dominate the face-on type complexes.