Introduction: Chronic conditions are the leading causes of death and disability worldwide. Providing care to people diagnosed with a chronic disease is challenging, and controlling multiple chronic conditions (MCCs) can be overwhelming, particularly in rapidly aging societies. The objective of this study was to examine the prevalence of MCCs from 2000 to 2010 in Taiwan. Methods: A random sample of 1 million representative National Health Insurance beneficiaries in 3 years (2000, 2005, and 2010) was obtained from the Taiwan National Health Insurance Research Database to examine the prevalence of MCCs. Chronic Condition Indicator and Clinical Classifications Software were used to determine and classify codes from the International Classification of Diseases, Ninth Revision. People who had 2 or more conditions among the 15 categories of conditions were defined as having MCCs. Results: The prevalence of MCCs increased from 9.6% in 2000 to 17.1% in 2010. The highest prevalence of MCCs was found among people aged 65 years or older (42.3% in 2000 and 64.5% in 2010, a relative increase of 52.5%). However, the highest rate of increase was found among people younger than 18 years (0.5% in 2000 and 1.6% in 2010, a relative increase of 220.0%). Conclusion: MCCs are increasingly prevalent among the older (≥65 y) population and among children and adolescents. Prevention and early intervention programs targeted to certain age groups may be required. If the increase in MCCs continues rapidly, the management of people diagnosed with MCCs would challenge the capacity of the health care system in Taiwan.