目標：探討台灣急性精神病床住院市場競爭程度及其他因素對精神病患精神科急性住院利用之影響。 方法：以民國90年身份證加密之全民健保精神科住院申報資料，主診斷ICD-9-CM介於290-319之急性精神病床住院病患為對象。市場區域以縣市為單位，市場競爭程度採用賀芬達指標，市場佔有率分別以住院費用及住院日計算之。 結果：53.89%急性精神住院病患在高競爭地區住院。病患就醫市場之競爭程度愈高，病患住院費用、每人日住院費用、14與30日再住院情形較高，其住院日較中度競爭地區病患短。住在私立醫院之病患住院費用、每人日住院費用、住院日較住公立醫院者低、但再住院情形較高。住在評鑑層級愈高的醫院，住院費用、每人日住院費用、住院日愈高，再住院情形較低。住在精神專科醫院之住院費用、每人日住院費用、住院日較住在綜合醫院精神科高，但30日再住院情形較低。住在醫院規模愈大的醫院，住院費用愈高、住院日愈短、再住院情形愈高。 結論：精神醫療市場存在非價格競爭，市場競爭程度愈高，急性住院病患醫療利用愈高，建議政府應注意高度競爭地區的監控，尤其是私立醫院、醫院層級愈低、規模愈大醫院的再住院率，以確保病患照護品質與減少醫療支出。

　　　　　Objectives: To investigate the effects of psychiatric market competition and other factors on acute psychiatric inpatients in Taiwan. Methods: The data (with scrambled IDs) of the inpatients from 2001 was derived from the National Health Insurance database. The primary diagnosis code numbers of ICD-9-CM were between 290 and 319. The market area of psychiatric service was based on city or county, and the Herfindahl-Hirschman Indexes were based on the amount of acute inpatient cost and the length of stay. These indexes were used to represent the degree of the competitive psychiatric market. Results: 53.89% of acute inpatients fall into areas with a highly competitive psychiatric market. Patients located in the area of a highly competitive psychiatric market had a higher cost per case and cost per diem as well as a higher rate of 14 & 30 days readmission, however, length of stay was shorter than of medium level competitive market (p<0.05). Regarding the ownership of hospitals where patients were admitted, although the inpatient cost per case, cost per diem, and length of stay in private hospitals were all lower than in public hospitals, 14 & 30 days readmission were actually higher than in public hospitals (p<0.05). The inpatient cost per case, cost per diem and length of stay in medical centers were higher than in regional and district hospitals (p<0.05). Nevertheless the 14 & 30 days readmission of patients in medical centers was lower than in regional and district hospitals. The inpatient cost per case, cost per diem and length of stay at psychiatric hospitals was higher than general hospitals with psychiatric sections, but had lower 30 days readmission rates (p<0.05). On the size of hospitals, the inpatient cost was higher, length of stay was shorter, and 14 & 30 days readmission were higher in larger sized hospitals than in smaller sized hospitals. Conclusions: There is non-price competition in the psychiatry market. The government should pay attention to the market of acute bed care in order to reduce readmission rate. This is especially the case for hospitals in areas with a highly competitive psychiatric market.