||Hardiness is an individual characteristic which allows to coping with life stressors and turning them into advantages (Kobasa, 1979; Maddi, 2006). Their components of Commitment, Control & Challenge can protect the athletes against the unpredictable circumstances of endurance running. The purpose of this study was to compare for the first time the hardiness levels between two groups of endurance runners and to determinate if this levels were related with a successful race performance. Volunteers 130 (69 ultra trail and 61 10. 06K) runners, ranged in age from 20 to 56 years (M = 35. 4, SD = 7. 3), who completed the 30-item Hardiness for Marathoners Scale (EPRM) (Jaenes, Godoy and Román, 2008) during the day race. Mean analysis comparison revealed that there was no differences in hardiness levels between the two groups (Z = . 280, p = . 77), the fastest ultra trail race times were independent from high hardiness levels (r = -. 072, p = . 30). Moreover, no differences in hardiness were found between ultra runners who finished the race and those who drop out (p = . 78). The results suggest that high Hardiness levels are a psychological characteristic of long distance runners. Furthermore, sport performance was not related with high Hardiness levels.