Using prospective data from the National Institute of Mental Health (NIMH) Epidemiologic Catchment Area surveys, we examined the relationship of depressive symptoms among patients seen by general medical practitioners, with the subsequent development of major depressive disorder. The goals of the analysis were to determine 1) the 1-year psychiatric status of these individuals, and 2) to evaluate factors associated with the risk of major depressive disorder (MDD) or dysthymia. Between 1980 and 1984, collaborators of the NIMH Epidemiologic Catchment Area program recruited 18,571 adult participants after probability sampling of census tracts and households in five metropolitan areas. To assess the occurrence of psychiatric conditions over time, staff administered the Diagnostic Interview Schedule soon after sampling and again at follow-up 1 year later. For this analysis, the study sample was limited to respondents who reported seeing a general medical physician in the previous 6 months and who were free of current depressive disorder at the baseline interview. Overall, 41% of the general medical patients reported experiencing at least one depressive symptom in the past 6 months. Between 3 and 5% of the individuals with depressive symptoms developed MDD or dysthymia at the follow-up interview. Although individuals with depressed mood had a slightly higher estimated relative risk compared with individuals with vegetative, or nonvegetative (cognitive) depressive symptoms, no single classification of symptoms was appreciably more likely to signal MDD or dysthymia 1 year later. However, the risk of depression increased with the number of depressive symptoms reported.(ABSTRACT TRUNCATED AT 250 WORDS)