Objective: The National Health Insurance (NHI) system in Taiwan is characterized by 1) free choice of physicians and health care facilities without formal referral; 2) generous drug benefits; and 3) low co-payments. The NHI beneficiaries thus exhibit features of frequent attendances, frequent changes of physicians, and a higher number of drug items in a prescription. It is interesting to know how likely a doctor shopper is to be a patient of polypharmacy. Methods: The data sources came from the historical claims datasets of 200,000-person cohort in 2005, offered by the National Health Insurance Research Database in Taiwan. The analysis was limited to the ambulatory records with conditions of chronic diseases, represented by visits with more than seven days of drug supply. For those people with at least one visit for chronic diseases, the degree of correlation between the total number of consulted facilities and the total number of distinct prescribed drug items in all visits for chronic diseases in 2005 would be determined. Results: Of the study cohort 56,956 people (30,070 females and 26,886 males; mean age 49.9 ± 19.9 [SD] years) had at least one visit for chronic diseases in 2005. On average, one of these people had paid 6.8 ± 7.0 (max. 98) visits, consulted 1.5 ± 0.9 (max. 32) facilities, and received 7.3 ± 7.3 (max. 93) distinct drug items for chronic diseases in a year. The total number of consulted facilities for chronic diseases in a year was strongly correlated with the total number of distinct prescribed drug items in all visits for chronic diseases in a year (Spearman's rho 0.548, p<0.001 [2-tailed]). Conclusion: More visits for chronic diseases at different facilities were related to more drugs prescribed. Besides the patients' reasons, the causes inherent in the health care system deserve investigations.