The aim of the study was to assess the adjunctive effects of orlistat on weight loss and the influence of weight reduction on glycaemic control in overweight Chinese female type 2 diabetic patients. A randomised, placebo-controlled, double-blind, 12-week study was conducted. Chinese female type 2 diabetic patients, overweight (body mass index > 25 kg/m2), poorly controlled glucose levels [glycosylated haemoglobin (HbA1c) > 8%], were randomly assigned to two groups. In addition to their oral hypoglycaemic agents (maximal doses of sulphonylureas and metformin), one group (n = 30) received a placebo and the other (n = 30) received orlistat 120 mg t.i.d. for 12 weeks. Comparing the changes that occurred after 12 weeks in the orlistat and placebo groups, the former showed significantly greater reduction in bodyweight (2.5 vs. 0.4 kg; p < 0.05), fasting plasma insulin level (p < 0.01), 2-h postprandial blood glucose after glucose challenge (p < 0.01), insulin resistance (p < 0.01), HbA1c (p < 0.05), total cholesterol and triglyceride levels (p < 0.05, respectively). No significant differences were found between treatment groups in blood pressure and heart rate. The addition of orlistat to oral hypoglycaemic agents resulted in a significant weight reduction and improvement of metabolic control in overweight Chinese female type 2 diabetic patients.