Stress such as inflammation produces an acute phase response that includes elevated levels of ceruloplasmin, the main copper component of plasma. Inflammatory effects on cellular copper enzyme activity levels are largely unknown. Cu-Zn superoxide dismutase (SOD) activities in liver, the main site of ceruloplasmin secretion, decreased with turpentine-induced inflammation (0.1 mL, intramuscular, leg) in rats fed any of three copper levels (adequate = 6 mg/kg, marginal = 2.5 mg/kg and deficient less than 0.5 mg/kg). Ceruloplasmin activities rose significantly with inflammation in the adequate and marginal groups but not in the deficient animals. Hepatic Cu-Zn SOD immunoreactive protein levels were unaffected by copper status or inflammatory state. Erythrocyte Cu-Zn SOD activities were influenced by dietary copper but not inflammation. An additional group of rats fed 15 mg copper/kg did not show a turpentine-induced decrease in liver Cu-Zn activity levels. Inflammatory effects on other copper enzyme activities did occur as evidenced by increases in ceruloplasmin and decreases in serum extracellular SOD. In conclusion, an acute phase response in rats increased the amount of dietary copper required to maintain hepatic Cu-Zn SOD activity at levels equal to those of nonstressed, copper-adequate rats. Rat erythrocyte Cu-Zn SOD activities provided a blood measurement reflective of copper intake with or without stress, but these values did not reflect decreases in liver Cu-Zn SOD activities after 3 d of inflammation.