The aim of this study is the analysis of different descriptors and reactions related to the experience of fatigue. Two groups were compared: a clinical sample (n = 92, 31 males, mean age = 38.87) and a non-clinical (n = 225, 135 males, mean age = 32.45) sample. The total sample was composed of 317 participants (52% males), ranging in age from 18 to 76 years. Findings show the experience of fatigue was mainly related to somatic terms (76% of the total sample). Specific results were found only for the clinical group: (a) significant relationships between fatigue and anxiety, χ2(1) = 34.71, p < .01; tension, χ2(1) = 16.80, p < .01; and sadness, χ2(1) = 24.59, p < .01; (b) higher intensity of fatigue (F = 84.15, p = .001), and predominance of the cognitive components of fatigue. Results showed that fatigue in subjects with a clinical disorder (versus those without) was associated both, to negative emotional states, and to a higher intensity of fatigue, especially in its cognitive elements. Important clinical implications for its assessment and intervention are discussed.