OBJECTIVES: A purpose of this study is to assess health resource utilization of  patients with osteoporosis in Thailand.METHODS: Electronic-based hospital records of patients with primary and secondary diagnosis of osteoporosis or patients taking osteoporotic drugs during 1st October 2002 – 30th September 2003 were retrieved from Phramongkutklao tertiary hospital. The researchers estimated the out-patient (OP) costs and in-patient (IP) costs for each individual patient using the cost to charge ratio. RESULTS: Hospital records of 2302 patients were reviewed. Of those, there were only 435 patients (19%) with diagnosis of osteoporosis. An average age of the patients was 64 years and 83% of them were females. Two-third of them had, at least, one co-morbidity. The co-morbidities include hypertension (27%), metabolic disorders (21%), and osteoarthritis (12%).  Each osteoporotic patient had average OP visits of 8.64 times per year of which half of the visits (50%) were related to osteoporosis treatments. The average unit cost per OP visit related to osteoporosis was BAHT4,148, which was a much higher than the average OP visit for conditions not related to osteoporosis (BAHT1300). Each patient had average IP visits of 1.27 admissions per year. Of these, 10% of total admissions were due to hip fractures, following with vertebral fractures (2%) and wrist fractures (0.6%). The unit cost per IP visit was highest for hip fracture (BAHT67,891/admission). The annual cost of OP and IP visits occurred at Phramongkutklao hospital among osteoporotic patients was BAHT53 and BAHT30 million, respectively. These accounted for 5% of the annual hospital account. CONCLUSIONS: Patients with osteoporosis had a much higher rate of hospital utilizations compared to the general population at a similar age group. The majority of health care cost occurred at OP visit. This was partly due to a high-cost of osteoporosis medications. These findings can be useful for the future assessments of value for money of health interventions for primary and secondary preventions of osteoporosis.