AbstractÐIn this study the authors try to clarify the ambiguities in previous studies on demographic and social factors and fatigue. We have divided people with fatigue complaints and associated symptoms into those who have chronic and non-chronic complaints, and into men and women. The research is based on diaries kept by Dutch citizens over a 21-day period, and uses univariate and discriminant analyses. The results show the utility of strati®cation for chronicity, gender and age. Compared to nonchronically fatigued subjects (NCFd) the chronically fatigued subjects (CFd) reveal multiple sources of vulnerability: physical, psychological, psycho±social and socio±economic. They report more days of fatigue, they tend to be older, and their physical health is characterized by signi®cantly more acute complaints and chronic disease. Their sum scores on psychological and psycho±social problems are above average. Their health histories are worse, they express greater feelings of frustration and irritation due to their ailments and report more health-related initiatives. The socio-economic pro®le of the CFd is disadvantaged: their educational level, occupational classi®cation and income are lower than that of the NCFd, and they are more frequently unemployed. CFd women are more frequently divorced or widowed than NCFd women. The factors predicting chronic vs non-chronic fatigue vary with the age and gender of the population. It is easier to predict non-chronic than chronic fatigue. Additional strati®cation within the group of CFd is recommended. #