Social phobia in the environment of poverty and major social inequalities, as observed in most developing countries, has received little attention. This population-based study was carried out in a poor community in Brazil (15,000 inhabitants), aiming at determining the prevalence of social phobia and its associated factors. The Composite International Diagnostic Interview was applied in a random sample of 1037 residents aged > or = 18 years. The 1-month, 1-year and lifetime prevalence of social phobia were 7.9, 9.1 and 11.8%, respectively. One-month social phobia was independently associated with age (45-64 years), marital status (divorced/separated), worse socioeconomic indicators (family income and education), number of months worked, worse health status and use of health services and medications. There was an important burden of social phobia in the study community, due to its high prevalence (similar or superior to those observed in most developed countries), and due to its association with worse health status and use of health services and medications. The strong association between social phobia and socioeconomic circumstance, even in a small and poor community, is certainly a reflex of the major social inequalities in Brazil.