Ethiopian runners are famous for their achievements in long-distance running. The recent immigration of Ethiopians to Israel provided an opportunity to compare some physiological variables between elite Ethiopian and white Israeli runners. Six Ethiopian and five white Israeli runners, aged 20 to 40 years, were studied before and after an 11 km race. Venous blood was sampled from each runner prior to the race, and 1 h, 48 h, and 5 days following the race. The activities of creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) were measured, and levels of serum electrolytes, urea, creatinine, phosphorus, albumin, cholesterol, and alkaline phosphatase were also determined. CK activity rose 2.6-fold with a peak 5 days after the race. LDH and AST levels rose as well (1.4-1.3-fold, respectively). Significant elevations also occurred in serum phosphorus, uric acid, and creatinine concentrations 1 h after the race. In contrast to previous studies in which higher enzyme activities were reported in blacks, we did not detect any difference in serum enzyme values between black and white runners.