Recent reports have suggested that running economy (RE) defined as oxygen consumption at standardized treadmill speeds may be an important determinant for successful distance running performance. The purpose of this study was to examine the additional role, if any, played by anaerobic factors in distance running performance. Highly trained male cross-country runners (N = 12) were administered a battery of standardized aerobic and anaerobic laboratory evaluations. Maximal oxygen uptake (&OV0312;O2max) and RE (ml · kg-1) were measured using open circuit spirometry during treadmill exercise. RE was measured at 241 and 295 m·min-1, and ventilatory threshold (Tvent) was determined and verified using a number of non-invasive ventilatory measures (&OV0312;E, &OV0312;E/&OV0312;O2, &OV0312;E/&OV0312;CO2, &OV0312;CO2, FECO2). Anaerobic measures included the Margaria power test and the Monod critical power test to determine anaerobic work capacity (AWC). The data were subjected to a SAS-STEPWISE analysis which combines stepwise addition and backward elimination and were used to predict performance time in a 8.05-km (5-mile) cross-country race in which all the runners participated. The subjects averaged 26.21 min for the 8.05 km run, with 72.1 ml · kg-1· min-1for the &OV0312;O2maxwith a Tventat 60.4 ml · kg-1· min-1(84% &OV0312;02max). AWC (Monod) was 17400 Joules with a range of 8,000–28,400 Joules. The STEPWISE procedure reveals that AWC contributes significantly (P< 0.003) to a 3 variable model predicting race performance (R2= 0.76,P< 0.01). AWC accounts for 58% of total shared variance with &OV0312;O2maxand an indirect measure of Tventaccounting for the remaining 17%. The results of this study underline the importance of a multifactorial approach to predicting race performance and the contribution of anaerobic systems to success in cross-country race performance.