The prevalence of varicose veins (VV) and of chronic venous insufficiency (CVI) was studied among 1755 adults over 15 years of age (443 men and 1312 women). These people attended the University Health Center in Botucatu, a country town in the State of Sao Paulo, Brazil, for routine examination or for any disease complaints. The prevalence of all grades of VV not including telangiectasis and reticular varices grade I was 47.6% (37.9% in men and 50.9% in non-pregnant women). The prevalence of VV recorded as moderate or severe was 21.2%. The more severe form of CVI with active or healed ulcer was present in 3.6% of the subjects (2.3% of men and 4% of women). For only 5.5% of the patients was VV or CVI the reason for medical consultation. The prevalence of VV increased with age and number of pregnancies and was greater among white than non-white people. Working posture or posture adopted for defaecation did not influence the prevalence of VV. Our data show the prevalence of VV and CVI to be higher or as high as the prevalence found in developed western countries. We therefore propose that studies of these conditions should be included in epidemiological surveys of other developing areas or countries, so that if data similar to ours are verified prophylaxis and early treatment could be included in health planning for these areas with the aim of reducing future morbidity and the related social onus.