Subsurface　contamination　at　petroleum-contaminated　sites　is　posing　a　serious　threat　to　the　environment　and　the　public　and　is　acquiring　more　and　more　attention　by　governments　and　industries.　This　paper　proposed　a　fuzzy　risk　assessment　method　and　its　application　to　a　petroleum-contaminated　site.　The　method　consists　of　three　parts:　(i)　calculation　of　fuzzy　steady-state　contaminant　concentrations　in　the　aquifer　based　on　an　analytical　solute　transport　model,　(ii)　possibilistic　analysis　of　fuzzy　criteria　for　different　risk　levels,　and　(iii)　environmental　risk　assessment　based　on　the　Euclidean　method.　The　method　can　effectively　reflect　fuzzy　natures　of　environmental　quality　at　a　site　and　evaluation　criteria　for　different　risk　levels.　Results　of　an　illustrative　case　study　indicate　that　environmental　risks　at　a　petroleum-contaminated　site　can　be　effectively　evaluated　through　the　developed　methodology.　The　assessment　results　are　useful　for　the　related　site　remediation　and　management　decision.