The aging process is associated with an increasing prevalence of osteoporosis and atherosclerosis, but it is uncertain if these two conditions are interrelated. Serum paraoxonase-1 (PON1) is a high-density lipoprotein (HDL) associated enzyme that has been implicated in the pathogenesis of atherosclerosis. Our aims of the study were to investigate (1) serum paraoxonase and arylesterase activities and, lipid hydroperoxide (LOOH) levels in healthy postmenopausal women and (2) whether there were any associations between these enzyme activities and bone mineral density (BMD). A total of 97 generally healthy postmenopausal women were enrolled in the study. BMD was measured at lumbar spine (LS) and femoral neck (FN) with dual energy X-ray absorptiometry. Serum paraoxonase and arylesterase activities were measured spectrophotometrically. LOOH levels were measured by iodometric assay. In this population, 50 (51%) women had BMD T scores < -2.5 at the LS and/or FN defined as osteoporosis and 47 (49%) of them had normal BMDs. Serum paraoxonase, arylesterase, and LOOH activities were not significantly different between osteoporotic and nonosteoporotic postmenopausal women. There were also no correlations between paraoxonase, arylesterase, LOOH activities, and LS BMD and FN BMD. We conclude that there may be not good evidence to support a direct relationship between osteoporosis and atherosclerosis in these subjects. However, prospective studies with larger groups are needed to investigate this issue further.