The rate of biotransformation of toluene in unconsolidated subsurface material from sites at Lula, Oklahoma, USA and Conroe, Texas, USA was compared to the ATP (adenosine triphosphate) content of these materials. The rate of toluene degradation decreased with decreasing ATP content. When ATP contents were at or less than 0.05 ng/g, biotransformation of toluene could not be detected (less than 1% of the initial concentration was degraded per week). At intermediate concentrations of ATP, 0.37 and 0.16 ng/g, the rates of toluene degradation were 18 + or - 4.5% and 25 + or - 10% of the initial concentration per week. At ATP concentrations above 1 ng/g, the rates of toluene degradation exceeded 90% of the initial concentration per week. There was no simple relationship between ATP content and chlorobenzene degradation. Subsurface material that had been exposed to creosote wastes, and which degraded toluene rapidly, also degraded benzene, o-xylene, and m-xylene.