The purpose of this study was to contribute the improvement of nursing staff development by implementing of effective and organized orientation program using the measure of effectiveness in the application of preceptor program with the reduction of the time of New entry nurse orientation. The subjects were comprised of 116 new entry nurses(59 new entry nurses were employed at June, 1996 and 57 at May & July, 1997) and 79 preceptors, who were in charge of new entry nurse orientation at 1997. These date were collected from June 18, 1996 to August 29, 1997. The characteristics of questionairs applied in this study were general characteristics(7 questions), knowledge of nursing care(138 questions); attitude toward her profession(40 questions) and the degree of satisfaction for the program(5 questions). The questionnairs were developed by the researchers of Asan Medical Center. The Check-list for basic nursing skill were used for the measurement of nursing skill which was developed by nursing department of AMC. The data were analyzed for the mean, standard deviation, difference of mean, ANOV A & t-test. The results of this study are as follows : 1) The changes in knowledge of nursing care : After three months of training the difference of mean between before and after the orientation was higher than the result of two month period training. However, the result was insignificant(p= .469). 2) Performance in nursing practice : Two month period orientation was more effective than three-month training period, however, the statistical significance can not be reached than 3 month period, which resulted in insignificant difference(p=.150). 3) The change in attitude toward her profession : After three-month of orientation, the difference of mean between before and after the orientation was higher than 2 month period orientation, which resulted in significant difference (p=.000). 4) The degree of satisfaction for the program with the time of new entry nurse orientation : After two-month of orientation, the mean of points was 2.57 where the score is higher than 3 month period with mean of 2.30. It resulted in significant difference(p=.000).