A randomized, single-blind, controlled trial was conducted to examine the effects of guava fruit intake on BPs and blood lipids in patients with essential hypertension. Of 145 hypertensives that entered the trial, 72 patients were assigned to take a soluble fibre and a potassium-rich diet containing 0.5-1.0 kg of guava daily (group A) and 73 patients to their usual diet (group B), while salt, fat, cholesterol, caffeine and alcohol intake were similar in both groups. Mean age, mean body weight and male sex, were similar, and so were risk factors, mean BPs, mean serum sodium, potassium, calcium, magnesium, triglycerides, cholesterol and HDL-cholesterol in both groups. Dietary adherence to guava intake was checked by a questionnaire. After four weeks of follow-up on an increased consumption of dietary potassium and low sodium/potassium ratio, group A patients were associated with 7.5/8.5 mmHg net decrease in mean systolic and diastolic pressures compared with group B. Increased intake of soluble dietary fibre (47.8 +/- 11.5 vs. 9.5 +/- 0.85 g/day) was associated with a significant decrease in serum total cholesterol (7.9%), triglycerides (7.0%) and an insignificant increase in HDL-cholesterol (4.6%) with a mild increase in the ratio of total cholesterol/HDL-cholesterol in group A patients compared with group B. It is possible that an increased consumption of guava fruit can cause a substantial reduction in BPs and blood lipids with a lack of decrease in HDL-cholesterol due to its higher potassium and soluble fibre content, respectively.