研究目的在探討某醫學中心護理人員之留任時間並找出影響留任時間之主要因素。研究方法採回溯世代研究設計，以南部某醫學中心的護理人員為研究對象，回溯期間為2007年1月到2011年3月，共1747人。統計方法以生命表（Life Table）、Kaplan-Meier及Cox迴歸（Cox regression）分析。研究結果為1.以51個月來看護理人員的月離職率只有4個月接近2%，建議月離職率應訂在1%；2.以51個月來看，公職護理人員任職醫院時間約1481天，契約護理人員約1049天，以任職醫院時間來看，契約護理人員比公職護理人員將近少了450天。本研究建議護理人員月離職率應訂在1%、醫院應該要爭取護理人員更多公職的職缺。

The purpose of this study was to understand the retention time of nurses in a medical center and identify the main factors contributing to the retention. The retrospective Cohort study design was adapted for this study using Life Table, Kaplan-Meier and Cox regression analyses. The research subjects of this study were 1,747 nurses in a medical center with duration from January 2007 to March 2011. The results showed that: 1) The monthly turnover rate was about 1% in the past 51 months and there were only 4 months with 2%. 2) There were two identities for the nursing staffs: one was civil servant nurses and the other was non-civil servant nurses. The civil servant nurses had 1,481 retention days during 51 months, much higher than non-civil servant nurses. The non-civil servant nurses had 1,049 retention days. 3) The retention of civil servant nurses was 6.25 times the retention of non-civil servant nurses. This study suggests that the reasonable monthly turnover rate is 1%. It is highly recommended that hospitals should have more job openings for civil servant nurses than non-civil servant nurses.