As part of the INTERSALT study, blood pressure, urinary electrolytes, age, and body mass index were assessed in a sample of 195 Yanomamo Indians from the Brazilian Amazon. Mean sodium excretion was 0.9 mmol/24 hr. Urinary sodium was lower than 1 mmol/24 hr in 84% of participants. Mean blood pressure was 96.0/60.6 mmHg (range 78/37 to 128/86). Systolic and diastolic blood pressure were not higher at older than at younger ages in men. In women, systolic pressure was lower at older ages. Mean body mass index was low (20.8 in women and 21.5 in men), and there was no alcohol intake reported. Mean 24 hour urinary potassium was 60 mmol in women and 67 in men. In the presence of the low sodium intake among the Yanomamo, body mass index and potassium, found to be related to blood pressure in the overall INTERSALT study, were not consistently related to pressure in this population. Results demonstrated that there was low average population blood pressure, no hypertension and no positive slope of blood pressure with age in a population with very low salt intake.