This study was performed to investigate the petroleum hydrocarbon (PH) degradative potential of indigenous microorganisms in ozonated soil to better develop combined pre-ozonation/bioremediation technology. Diesel-contaminated soils were ozonated for 0-900 min. PH and microbial concentrations in the soils decreased with increased ozonation time. The greatest reduction of total PH (TPH, 47.6%) and aromatics (11.3%) was observed in 900-min ozonated soil. The number of total viable heterotrophic bacteria decreased by three orders of magnitude in the soil. Ozonated soils were incubated for 9 weeks for bioremediation. The number of microorganisms in the soils increased during the incubation period, as monitored by culture- and nonculture-based methods. The soils showed additional PH-removal during incubation, supporting the presence of PH-degraders in the soils. The highest removal (25.4%) of TPH was observed during the incubation of 180-min ozonated soil during the incubation while a negligible removal was shown in 900-min ozonated soil. This negligible removal could be explained by the existence of relatively few or undetected PH-degraders in 900-min ozonated soil. After a 9-week incubation of the ozonated soils, 180-min ozonated soil showed the lowest TPH concentration, suggesting that appropriate ozonation and indigenous microorganisms survived ozonation could enhance remediation of PH-contaminated soil. Microbial community composition in 9-week incubated soils revealed a slight difference between 900-min ozonated and unozonated soils, as analyzed by whole cell hybridization. Taken together, this study provided insight into indigenous microbial potential to degrade PH in ozonated soils.