The influence of change in land-use from native vegetation to pasture (20-71 yr after conversion), and subsequent change from pasture to eucalypt plantation (7-10 yr after conversion) on soil organic matter quality was investigated using 13C CP/MAS NMR spectroscopy. We studied surface soil (0-10 cm) from six sites representing a range of soil and climate types from south-western Australia. Total C in the samples ranged from 1.6 to 5.5%, but the relative proportions of the four primary spectral regions (alkyl, O-alkyl, aromatic and carboxylic) were similar across the sites, and changes due to land-use at each site were relatively minor. Main impacts of changed land-use were higher O-alkyl (carbohydrate) material under pasture than under native vegetation and plantation (P=0.048), and lower aromatic C under pasture than under native vegetation (P=0.027). The decrease in aromatic C in pasture soils was related to time since clearing.