Fifty consecutive patients (45 women and 5 men) with pustulosis palmoplantaris were evaluated for thyroid disease. Five women had previously had thyroid disorders for which they were receiving thyroxine substitution therapy. Of the other 40 women three had a raised serum concentration of thyroid-stimulating hormone and nine had high concentrations of antibodies against thyroid "microsomal antigen." During a 4-year follow-up hypothyroidism developed in two women with initially raised thyroid-stimulating hormone, and laboratory test results for one woman indicated subclinical hyperthyroidism. Four of nine patients with thyroid abnormality also had evidence of gastric autoimmunity. Of the patients 94% smoked at the onset of pustulosis palmoplantaris compared with 33% in age- and sex-matched healthy controls. The prevalence of thyroid disease in women with pustulosis palmoplantaris was significantly higher than in a comparable population sample of women from the same geographic region. We conclude that patients with pustulosis palmoplantaris should be screened for thyroid disease.