The aim of this study was to examine the relative contributions made by medical morbidity, psychiatric disorder, functional status, and hypochondriacal attitudes to medical patients' opinions of their overall health status. The study was conducted in the general medical clinic of a large academic teaching hospital. Consecutive clinic visitors on randomly selected days were screened with a hypochondriasis self-report questionnaire, since the overall project was designed as a study of hypochondriasis. A random sample of the patients below a pre-established cutoff (n = 100), along with all those exceeding the cutoff (n = 88), returned to undergo a research battery. For this analysis, a representative sample of the entire clinic was reconstituted by weighting the data from patients above and below the screening cutoff in proportion to their prevalence in the clinic. Measures of psychiatric disorder (the Diagnostic Interview Schedule), personality disorder, functional status and disability, medical morbidity (from physician ratings and medical record audit), and hypochondriacal attitudes were obtained. Patient self-ratings of global health status were significantly correlated with aggregate medical morbidity (r = 0.36; P less than 0.001); psychiatric morbidity (r = 0.48; P less than 0.001); functional disability (for intermediate activities of daily living, r = 0.62; P less than 0.001); hypochondriacal attitudes (r = 0.79; P less than 0.001); and with the tendency to somatize (r = 0.77; P less than 0.001). Using multiple regression analysis, the most powerful correlates of perceived global health were hypochondriasis, somatization and disability (model R2 = 0.762).(ABSTRACT TRUNCATED AT 250 WORDS)