The toxic potential of manufactured gas plant residue (MGP) given in the diet to male and female B6C3F1 mice was evaluated. In addition, the bioavailability of chemical components of MGP were also investigated by monitoring polycylic aromatic hydrocarbon (PAH) metabolites in urine and DNA adduct formation in forestomach and lung tissue. Basal gel diets containing 0.05, 0.25, 0.50% MCP or 0.005% benzo[a]pyrene (BaP) were fed to animals for 94 and 185 d. Mice readily consumed adulterated diets without any evidence of acute toxicity. The total amount of MGP and BaP consumed by mice ranged from 118 to 2604 mg and from 12 to 29 mg, respectively. Male mice fed a control or BaP diet and female mice fed a 0.05% MCP diet had the highest body weight gains. Male and female mice fed a 0.50% MCP diet had the lowest body weight gains. The bioavailability of chemical components of MCP was evaluated by monitoring the urinary excretion of PAH metabolites by male mice fed a 0.25% MCP diet. 1‐Hydroxypyrene was determined by high‐performance liquid chromatography analysis to be the major fluorescent metabolite excreted by mice throughout the 185 d of diet administration. At necropsy, no chemical‐related gross lesions were detected. In addition, no treatment‐related microscopic lesions were evident in tissues obtained from animals fed a 0.50% MCP‐ or BaP‐adulterated diet. The ³²P‐postlabeling assay was used to evaluate MCP‐ and BaP‐induced DNA adduct formation in lung and forestomach tissue. The level of DNA adducts formed from the chemical components of MCP paralleled the amount of material ingested by animals. Lung DNA1 adduct levels were considerably higher than forestomach levels when mice ingested a 0.25% or 0.50% MCP diet. These studies demonstrate that the continuous ingestion of MCP or BaP for 185 d does not result in acute toxicity or chemical‐related lesions at doses up to 0.50% MCP or 0.005% BaP.