OBJECTIVES: To investigate bone responses to hormone therapy (HT) according to basal bone mineral density (BMD) and previous responses to HT, as well as the frequency and clinical characteristics of HT non-responders in Korean postmenopausal women. METHODS: We retrospectively reviewed a total of 1,836 postmenopausal women who received HT from seven university hospitals. BMD data at the lumbar spine (LS), femur neck (FN), femur trochanter (FT) and total hip (TH) before HT, and at one, two, and three years after HT were collected. All patients were divided into three groups according to basal BMD: normal, osteopenia, and osteoporosis. RESULTS: Women with a greater loss of BMD during the first year of HT were more likely to gain BMD in the second year at any of the four skeletal sites. Bone responses to HT during the third year were not related to the responses during the first year. Mean BMD changes during the first year were significantly higher in the osteoporosis group, but mean BMD changes during the second year were not different between three groups except in LS. The frequency of non-responder (annual BMD losses more than 3%) during the first year was significantly higher in the normal basal BMD group. Mean basal BMDs were higher in the two-year consecutive non-responder group at LS, FN and FT, but those of the three-year consecutive non-responder group were not significantly higher except in FN. CONCLUSION: Most women who lose BMD after HT are likely to gain BMD during the next year. The frequency of non-responders is higher in the higher basal BMD group, and patients with lower basal BMD will be likely to respond better to HT.