34S/32S ratios have been measured in a suite of samples from the stratabound, volcanogenic massive sulphide deposit at Woodlawn, N.S.W.34S values for the sulphides vary as follows: in the ore horizon, pyrite +6.7 to +9.2%. (mean +8.1‰), sphalerite +5.2 to +8.6‰. (mean+6.9‰),chalcopyrite +6.4 to +7.0‰ (mean +6.7‰) and galena +2.8 to +5.5‰ (mean +4.4‰); in the vein mineralization, the host volcanics—pyrite +8.7 to +11.4%. (mean +9.8‰), sphalerite +7.8 to + 10.3‰ (mean +9.2‰), chalcopyrite; +8.8 to +10.1‰ (mean +9.2‰) and galena +6.9 to +7.2‰ (mean +7.1‰). Barite from the upper ore horizon levels has an isotopic composition of +30.0‰, consistent with its having originated from Silurian ocean sulphate. The general order of34S enrichment in the sulphides is pyrite > chalcopyrite∼sphalerite > galena. Isotopic fractionations in the systems galena/sphalerite/pyrite and chalcopyrite/pyrite indicate an equilibration temperature of 275–300°C. This temperature is considered to represent that of sulphide deposition.