This study examines factors differentiating women and men who suffer from fatigue. It is based on diaries kept by Dutch citizens over a 21-day period between 1987-88. The majority of those with persistent fatigue complaints (PFs) were male, middle-aged, lower-educated and unemployed, and they had more psychological and psycho-social problems than the incidental fatigue sufferers (IFs). Factors differentiating the PFs from the IFs are not the same for both sexes. Moreover, on a number of socio-demographic variables PF men and women differed less from each other than IF men and women. Future research should focus on the gender-specificity of the factors that lead to the development of persistent fatigue.