A study was conducted to examine sex differences in subjective symptoms of fatigue in men and women with reference to the experience of awareness and cognitive appraisal based on symptom of fatigue content. A total of 54 questionnaire items were administered to 730 people (290 men and 440 women) . The subjects indicated whether or not they were aware of the content, and to what degree the content of the question for each item was important. Sex differences in the response to the ratio of awareness and the degree of importance were then. The mean importance scores for subjective symptoms of fatigue in men and women were 3.9-5.4 and 4.5-5.6, respectively. It was found that a majority of the men and women showed awareness of each item. A significant difference was recognized in the factor of awareness in all items as a result of two-way ANOVA of the degree of importance by which the presence of awareness and its sex difference were assumed to be factors, and those who were aware deemed the degree of importance high. On the other hand, the 28 items for which a significant sex difference was recognized showed a high value, and there was a marked content of Languor, Loss of Vigor, and A Feeling of Impatience and Physical Disintegration in women. In the same items, it was inferred that persons who were more aware than the persons who were not aware regarded subjective symptoms of fatigue as important. Most items in which a main effect of sex was recognized were content of Loss of Vigor and a Feeling of Impatience and Physical Disintegration. It was thought that women considered these symptoms more important than men. The sex difference in symptoms of fatigue was inferred to be due to the difference in the level of acknowledgment based on experienced knowledge.