The Barberton Greenstone Belt hosts abundant structurally controlled gold mineralisation of Mesoarchaean age. More than 300 gold occurrences have been reported, although most of the gold production so far (>350 tonnes Au) has come from a handful of deposits located along the northern margin of the greenstone belt. Most deposits are hosted by greenschist-facies metasedimentary and metamafic rocks, with the notable exception of the amphibolite-facies rocks at New Consort mine. Mineralisation is associated with quartz--carbonate veins that truncate major compressional structures at the greenstone belt scale. The age of mineralisation is loosely constrained at circa 3080--3030 Ma, based on U--Pb dating of hydrothermal rutile and titanite. In greenschist-facies deposits, the ore assemblage is dominated by pyrite and arsenopyrite, which contain up to thousands of ppm of `invisible' gold, Ni--As--Sb sulphides and native gold. At New Consort mine, mineralisation includes massive replacement-style ore and vein-hosted or disseminated types. Both structural studies in the field and microstructural observation point to a multistage ore deposition process, which is reflected in the re-activation of brittle to ductile structures and the overprinting of sulphide assemblages. The presence of mass-independently fractionated S isotopes ($\Delta$33S{\thinspace}={\thinspace}--0.6 to +1.0{\texttenthousand}) in pyrite from Sheba and Fairview mines suggests that hydrothermal fluids mobilised S from volcanic and sedimentary rocks of the greenstone belt and places constraints on the origin of the Au itself.