The progress of bioremediation of waste petroleum sludge at Chevron’s Perth Amboy, New Jersey, refinery landfarm was evaluated using a ranking scale based on refractory biological marker hydrocarbons that are indigenous to, and ubiquitous in, crude oils. Of the four samples analyzed from different locations in the landfarm, two were,virtually identical and showed an absence of the n-alkanes expected to be found in the sludge (light biodegradation ranking). Another showed additional partial degradation of acyclic isoprenoids, e.g., pristane and phytane (moderate ranking). The fourth sample showed complete n-paraffin and isoprenoid loss, partial alteration of hopanes, and losses of C-27 steranes, C-27 diasteranes, C-27 monoaromatic steroids, and C-26 triaromatic steroids relative to the higher steroid homologs in each of these series (heavy ranking). These results suggest a concomitant preferential loss of steroid hydrocarbons that have the cholestane side;chain and a possible new steroid biodegradation mechanism that is essentially blind to the structure of the steroid nucleus. The latter sample also showed levels of most polynuclear aromatic hydrocarbons (PAH), suggesting a buildup of these compounds as others were removed. However, some of the smaller PAH (acenaphylene, fluorene, fluoranthene) appear to have decreased. These results suggest that a protocol based on such a biodegradation ranking scale could be used to monitor the progress of bioremediation of oil based refinery wastes.