A large number of gold(I) thiolates, [Au(SR)], have been prepared in which the R group is an alkyl, aryl, carboxylic acid, amino acid, or heterocycle. Most are highly insoluble in all common solvents, but [Au(SC6H4R′-p)](R′= Et, Pri, Bus, or But) dissolve in organic solvents. The 1H and 13C n.m.r. spectra of the soluble compounds show several sets of signals, which coalesce to single sets at high temperature, consistent with the presence of fluxional, possibly pentameric, polymeric rings. The 197Au Mössbauer spectra are consistent with linear co-ordination of the gold by two sulphur ligands and, in agreement with the n.m.r. data, show broadening indicative of the presence of non-equivalent gold atoms. The therapeutic compounds appear to be structurally similar to the other gold(I) thiolates.