Major psychiatric disorder is more common in people of lower rather than higher socioeconomic status. This is less clear for the commoner, so-called minor psychiatric disorders, but these are more affected by tendency to report symptoms. To examine this the distribution of minor psychiatric disorder by employment grade measured by the 30-item General Health Questionnaire is reported from the first cross-sectional phase of the Whitehall II Study of 10,314 London-based civil servants, men and women between 35 and 55 years. Validation of the GHQ in a random subsample stratified by grade and sex (N = 201) suggested that people in lower employment grades tend to under-report minor psychiatric disorder on the GHQ relative to those in higher employment grades. The prevalence of minor psychiatric disorder corrected by the coefficients from the validity study was greater in the lower employment grades than the higher employment grades particularly for men. This was echoed in grade differences in well-being measured by the Affect Balance Scale, and in symptoms and recurrent health problems. Overall, for women there were few clear-cut differences in minor psychiatric disorder by employment grade. The lack of social class gradient in women suggests that further exploration should examine women's role at work and their personal lives for the aetiology of minor psychiatric disorder.