Objectives: The primary care system is responsible for the management and coordination of patient care. This study will explore how many primary care clinics are able to take on the functions of family physicians. This will be accomplished through exploring the patient complexity and the services provided by primary care clinics in Taiwan. Methods: In this study, we calculated patient complexity using different dimensions, including quantity, variability, and diversity. We assessed patient complexity in terms of diagnoses, exams, age distributions, medications, specific diagnosis and treatments provided by primary care clinics. In addition, we referenced the quality care indicators used in other countries and then summed up eleven primary care services indicators. Through linear regression and logistic regression, we examined the relationships between division, urbanization and patient complexity and services provided by primary care clinics. We also took into account the relationship between physicians' specialty, demographic characteristics, and primary care services. Results: Patient complexity is the highest for family medicine providers, followed by internal medicine and pediatrics clinics. In 2013, the results suggest that the eleven primary care services that primary care clinics can provide are: fasting blood lipids 36.45%, glycosylated hemoglobin 30.80%, microalbuminuria 25.53%, eye examination 8.69%, health examination 35.26%, influenza vaccine 21.53%, pap smears 8.31%, fecal occult blood test 18.7%, and smoking cessation clinic 7.46%. In cancer screening services, colorectal cancer screening are only 1.32%, and breast cancer screening only 0.17%. Fewer than 10% of primary care clinics provide the five most common services, and nearly 40% of those clinics did not provide any of the above services. In general, the degree of urbanization in the clinics is inversely proportional to the patient complexity and the ratio of clinics providing primary care services. Conclusions: Overall, family medicine, internal medicine and pediatrics clinics in Taiwan are able to take on the functions of primary care providers, but fewer than 10% of the primary care clinics provide top 5 primary care services. Ideally, primary care services could be spread more evenly between providers. Any effort to improve the referral system should be aimed at strengthening the clinics that aren't currently able to meet primary care service needs. This is particularly true of primary care clinics in highly urbanized areas.