The structure and energetics of the simplest vic-disulfoxide CH3S(O)S(O)CH3 and its key isomers are reported. Computational methods include a CASSCF[2,2] treatment with a large basis set on sulfur and oxygen, followed by multireference MP2 refinement, and also the hybrid density functional B3LYP. Calculations at the G3 level were also carried out. In contrast to previous reports, a weak bond does exist for both vic-disulfoxide diastereomers. A bond enthalpy near 20 kcal mol(-1) is reported. The isomeric sulfenylsulfinate is slightly lower in energy than the vic-disulfoxide. The B3LYP structure obtained for 5,5-di-t-butyltetrathiolane-2,3-dioxide reproduces the essential structural parameters of the one experimentally known vic-disulfinyl compound, 5-(1-adamantyl)-5-tert-butyltetrathiolane-2,3-dioxide.