Rhabdomyolysis was evaluated by measurement of total creatine kinase (CK) and lactic dehydrogenase (LDH) in 19 patients with severe sepsis; 12 developed acute renal failure (Group B) and 7 did not (Group A). Results were compared to 7 patients with trauma (Group C) and 6 patients with chronic renal failure and minor infections (Group D). CK was higher (p less than 0.005) in Group B than in A. Results in Group C were similar to those in A. Elevation of CK correlated to increases in creatinine (r = 0.655, p less than 0.005). CK levels of Group D patients were lower than those of Group B. Blood pressure, lactate and pO2 were similar in both groups but thrombopenia was noted in Group B patients. Our results suggest that rhabdomyolysis and thrombopenia play a role in the development of renal failure in patients with severe sepsis.