The objective of this study was to examine the effects of lovastatin on bone mineral density (BMD) of postmenopausal women with type 2 diabetes mellitus (DM). The study was an open-label clinical trial conducted from March 2002 to November 2003. Fifty-five postmenopausal women age 54-67 years with type 2 DM were allocated to lovastatin-treated and control (without lovastatin) groups based on low-density lipoprotein cholesterol (LDL-C) >130 or < or =130 mg/dl. The first group received lovastatin (20 mg daily titrated every 3 months to keep LDL-C less than 130 mg/dl) for a total of 18 months. The second group received their own diabetic regimen without statin. The BMD of the lumbar spine (L1 - L4), femoral neck, Wards triangle, trochanter and total hip was measured by dual-energy X-ray absorptiometry at baseline and after 18 months. In the 28 women treated with lovastatin, the BMD increased in lumbar spine (from 0.946 (0.122) to 0.978 (0.135) g/cm2, p<0.01) and Ward's triangle (from 0.685 (0.123) to 0.780 (0.186) g/cm2, p<0.01). In the 27 women not treated with statin, the changes in BMD at all bone sites were not statistically significant. BMD was higher in femoral neck (1.2% vs. -2.7%, p<0.05), Ward's triangle (13.9% vs. 3.3%, p<0.05), trochanter (-0.1% vs. -2.9%, p<0.05), total hip (1.2% vs. -1.4%, p<0.05) and lumbar spine (3.4% vs. 1.2%, p>0.05) at the end of the study. Treatment with lovastatin may prevent bone loss in postmenopausal women with type 2 DM.