Objective: 1) To study the effect of the mentor nurse system on performance of mentor nurses' role 2) To measure mentor nurses' satisfaction 3) To study problems and obstacles on the mentor nurses' role in the Department of Nursing, Songklanagarind Hospital.

Research design: Descriptive study.

Materials and methods: Data were collected from 31 nurses who had passed the mentor nurse system, 31 novice nurses working with them and 18 ward head nurses. The questionnaire had 2 parts: one to evaluate role of mentor nurses, and the other to evaluate the satisfaction of mentor nurses with this system.

Results: 1) The overall mean score of the role of mentor nurses was at a high level (X=3.99, SD=2.88) and the mean score of the role of mentor nurse given by novice nurses and mentor nurses was at a high level (X=4.20, SD=0.20, X=3.97, SD=0.25, respectively) and that of head nurses was at a low level (X=3.79, SD=0.25). 2) The mean score of satisfaction of mentor nurses was at a moderate level (X=2.93, SD=0.55). 3) The problems/obstacles of the role of mentor nurses were job burden, working together being limited by the changing period of mentor nurses and novice nurses, and poor cooperation in using the mentor nurses tool.

Conclusions: This study could be used to adjust the mentor nurse system in the Department of Nursing, Songklanagarind Hospital.