The results of a cross-sectional (prevalence) study of high blood pressure, carried out in 1987 in Araraquara County in the north of S. Paulo State, Brazil are presented. The group studies numbered 1,199 people, including 533 men and 666 women, of from 15 to 74 years of age. The results show a high prevalence of the disease (32.0% for men and 25.3% for women), with a tendency to increase with age, up to the 40's (men) and the 50's (women). There was also a greater percentage of hypertensives in the mulatto and black groups, in the obese, and among those of lower family income, with a lower level of schooling and with less well remunerated jobs. However, the logistic regression showed very small odds ratios associated with these risk factors, which could be attributed to the way these factors were considered.