OBJECTIVE: The prescribing of proton pump inhibitors (PPIs) had increased greatly in recent years worldwide. Aim of our study was to analyze the utilization patterns of PPIs within the National Health Insurance program in Taiwan from 1997 - 2000. MATERIAL AND METHOD: The systemic sampling data-sets from the National Health Insurance Research Database served as data sources. Units of measurement for PPIs were numbers of prescription items and defined daily doses (DDDs). To estimate the proportion of the population treated daily with PPIs, numbers of DDDs per 1,000 inhabitants per day were calculated. In order to realize the role of PPIs in treating Helicobacter pylori-related disorders, we also analyzed various combined prescriptions of PPIs with amoxicillin, clarithromycin, metronidazole, tetracycline and bismuth. RESULTS: In the study period, PPI prescriptions increased nearly 2-fold at the outpatient sector and more than 3-fold at the inpatient sector. Men received more PPI prescriptions, as a whole, than women. Most PPIs were prescribed at the outpatient sector: 93.9% in 1997, 92.3% in 1998, 90.4% in 1999 and 87.3% in 2000. The numbers of DDDs per 1,000 inhabitants per day for all kinds of PPIs were 0.59, 0.78, 1.07, and 1.13 from 1997 - 2000, respectively. While the percentage of monotherapy increased from 63.6% in 1997 to 75.5% in 2000, the combination therapies did not experience a rapid and sustained growth. Among the combination therapies, PPI + amoxicillin + metronidazole and PPI + amoxicillin were popular in 1997 and 1998, but triple therapy with PPI + amoxicillin + clarithromycin predominated in 1999 and 2000. CONCLUSIONS: Despite increasing use, prescribing volumes of PPIs in Taiwan were far fewer than those in other developed countries. Treatment of Helicobacter pylori-related disorders in Taiwan followed universal standard.