Stomatal conductance, phyllode water potential and total phyllode area were measured in provenance trials of Acacia auriculiformis in Kanchanaburi province, western Thailand. The data were collected daily and seasonally from 7-year-old trees. Provenances and trees selected for the measurement originated from three regions, i.e. Northern Territory (NT), Queensland (Qld) and Papua New Guinea (PNG). Physiological differences among the three provenances were small and not significantly significant. The Queensland provenance had the smallest tree phyllode area and the Papua New Guinea provenance the largest. Stomatal conductance and phyllode water potential were high during the wet season, and low in the dry season.