The relationship between postoperative weight loss after vertical banded gastroplasty in morbidly obese patients and preoperative serum triglycerides, cholesterol, HDL-cholesterol, uric acid and fasting plasma glucose was evaluated. The rate of weight loss, calculated as a percentage of original weight, was determined at three and six months after surgery. There was a significant correlation between rate of weight loss at three months and preoperative serum uric acid (r = -0.60, p less than 0.01). and also with the total cholesterol: HDL-cholesterol ratio (r = 0.61, P less than 0.01). At six months, the rate of weight loss correlated with preoperative serum triglycerides (r = -0.54, p less than 0.02) and total cholesterol: HDL cholesterol ratio (r = 0.44, p less than 0.05). The reasons for the predictive value of these biochemical parameters is unknown and deserves further study.