The present study sought to relate the well-being of night workers to that of the working population in general. One hundred and ninety-seven male permanent night security guards were interviewed with regard to the occurrence of various symptoms during the previous 12-month period. The results were compared with the results from similar interviews with a representative national sample of males (n= 1769) in the Swedish workforce. An age standardized morbidity ratio was computed with control for various background variables. The results showed that the security guards had a 2-3 times higher occurrence of sleep disturbances and fatigue than the national sample. Among the variables notdiffering from the national sample were gastrointestinal problems, headache, nervous problems, depression, nausea, diarrhoea, and haemorrhoids. It was concluded that sleep/wake disturbances are considerably more usual in permanent night security guards than in the working population as a whole.