BACKGROUND AND AIMS: Volatile organic compounds (VOCs) released into the air from eucalyptus have putative roles in chemical communications. But the types and concentrations released in nature, as well as the ecological functions of VOCs in soil water, have not been adequately investigated to date. METHODS: We developed some effective methods for the extraction of VOCs released by root exudation, foliage and leaf litter leaching, and leaf litter decomposition, into water extracts in the laboratory or from field soil around Eucalyptus urophylla. The VOCs were determined by GC-MS. Lolium multiflorum Lam. (annual ryegrass) and Bidens pilosa (cobbler’s pegs) were selected to test the phytotoxic effects of VOCs in soil water released from E. urophylla grown under natural conditions. RESULTS: Fourteen VOCs in soil water, released by foliage and leaf litter leaching and leaf litter decomposition, were identified and quantified. But we did not identify any VOCs from root exudates. When the concentrations of VOCs were reconstituted to mimic the soil conditions, the laboratory bioassays showed that seed germination and seedling growth of the tested plants were significantly inhibited. CONCLUSIONS: VOCs in soil water were phytotoxic when they had been released by foliage and leaf litter leaching and leaf litter decomposition from E. urophylla.