Abstract: The toxicity of various concentrations of cadmium on the growth of species of Bacillus and Pseudomonas on Nigerian light crude oil was investigated. Acclimation periods of the organisms in the crude oil broth were extended from 24 to 72 h depending on metal concentration and test organism. Growth rate at exponential phase was reduced from 0.16 to 0.026 h-1 in Bacillus sp. and 0.2 to 0.07 h-1 in Pseudomonas sp. High concentrations (1000 mg L-1) of cadmium selected resistant strains of Bacillus sp. which maintained a growth rate of 0.02 h-1 from 72 to 384 h of the study, whereas growth rate of Pseudomonas sp. decreased gradually throughout the study period. Some viable cells of Pseudomonas sp. died out during prolonged exposure to low concentrations (≤10 mg L-1) of cadmium, but nevertheless escaped spectrophotometric detection. The results from this study suggest that total viable counts data are more reliable in metal toxicity studies than optical density measurements of growth. The results obtained also showed that although Pseudomonas sp. was a better degrader of crude oil than Bacillus sp., the later would be more suitable for bioremediation of oil-polluted environments co-contaminated with cadmium, than the former.