Objectives-To determine the prevalence of fatigue in the general popul
ation and the factors associated with fatigue. Design-Postal survey. S
etting-Six general practices in southern England. Subjects-31 651 men
and women aged 18-45 years registered with the practices. Main outcome
measures-Responses to the 12 item general health questionnaire and a
fatigue questionnaire which included self reported measures of duratio
n, severity, and causes of fatigue. Results-15 283 valid questionnaire
s were returned, giving a response rate of 48.3%, (64% after adjustmen
t for inaccuracies in the practice registers). 2798 (18.3%) of respond
ents reported substantial fatigue lasting six months or longer. Fatigu
e and psychological morbidity were moderately correlated (r = 0.62). W
omen were more likely to complain of fatigue than men, even after adju
stment for psychological distress. The commonest cited reasons for fat
igue were psychosocial (40% of patients). Of 2798 patients with excess
ive tiredness, only 38 (1.4%) attributed this to the chronic fatigue s
yndrome. Conclusion-Fatigue is distributed as a continuous variable in
the community and is closely associated with psychological morbidity.