目的：本研究旨在評估一個大型醫院的成立，對當地基層診所造成的影響，藉以推論醫療市場的競爭情形。方法：以健保申報資料為依據，觀察臺北市某一大型醫院成立前後四年，對該區基層診所服務量與申報金額的影響，並以鄰近性質相近的一區為對照，進行比較分析。結果：本研究發現，在新醫院成立後，該區整體的門診服務量與申報金額明顯上升，醫院部分的門診量第一年即增加一倍，其後二年也持續成長。然而當地基層診所的營運狀況也呈現正成長，與對照組區比，並未發現因競爭激烈而有營運萎縮的現象。結論：基層診所的營運未受新醫院成立的影響，可能因為 當地原有供給不足的問題，也可能有醫師誘發需求的現象，而真正的原因仍有待進一步分析。

　　　　　Objectives: This study is to evaluate the impact of a newly opened hospital on the operation of local clinics and to understand the competition in health care market. Methods: A Taipei local area with a new hospital opening was chosen. Four years of outpatient services claim data from all local health care providers to the Bureau of National Health Insurance were analyzed. A nearby comparison area was employed in the analyses. Results: After the opening of the new hospital, the outpatient services volume d oubled in the first year and kept increasing in the following years in the research area. However, the operation of local clinics was not affected. Their service volume and expenses increased every year, which were comparable to the comparison area. Conclusion: The opening of a new hospital did not affect the operation of local clinics. Several possible explanations were discussed.