This review covers the crystallographic data of organotin compounds containing two tin centres, with a view to identifying correlations between properties and structure. Almost two hundred and fifty such compounds are included, of which almost thirty contain Sn 2 +6 units with a direct Sn-Sn bond, the shortest being 269.1(1) pm. There are ten compounds with tin in the +2 oxidation state, with a shortest Sn(ll)-Sn(ll) bond distance of 276.4(2) pm. The remainder of the compounds contain tin(IV), and the shortest Sn(IV)-Sn(IV) distance is 294 pm. The predominant geometries for tin(IV) are tetrahedral and trigonal bipyramidal. Distortion and cis-trans isomerism are found, the former being most common. In one example of distortion isomerism crystallographically independent molecules occur within the same unit. Several types of bridging are observed between the tin centres. Relationships between bond distances, ligand size and angles are discussed in the respective sections. The most common bridge donor atom is oxygen. The most common carbon donor ligands are phenyl and methyl groups.