The potential energy surface of diglyme has been investigated using ab initio molecular orbital theory. The all-trans conformer and 20 conformers having either one- or two-gauche conformations around C-C or C-O bonds were studied at the HF/6-31G(d) level. The four lowest energy structures were further investigated with larger basis sets and with inclusion of correlation effects. At the highest level of theory, the tg + g - t 3 conformer is 0.1 kcal/mol more stable than the all-trans conformer, while the tgt 4 and g + g - t 4 conformers are slightly less stable than the all-trans conformer.