Employees’ training can be effective in gaining experience and improving individuals’ function and can also guarantee the survival and perfection of the organization by strategic improvement. The main aim of the present research was to determine the effect of in-service training on trained employees’ efficiency from experts’ point of view in the central office of Arak medical University of Medical Sciences. This cross-sectional analytical study was carried out on 126 experts who had passed their in-service training courses in the central office of Arak University of Medical Sciences during 2001-2006. Data collection was carried out by a reliable and valid questionnaire including questions on occupational efficiency, satisfaction, skill and capability. Data are analyzed by descriptive statistical methods, independent t-test one-way variance analysis and Pearson correlation coefficient using SPSS 11.5 software. There was a significant correlation between in-service training courses and efficiency, occupational satisfaction, skill and capability (p< 0.001). Meanwhile, there was no significant relationship between the average scores of efficiency, satisfaction, skill and capability with the three levels of age (p= 0.48), education levels (p= 0.241) and employment duration levels (p= 0.218). In-service training courses will lead to promotion of employees’ efficiency level from experts’ point of view. Developing the employees’ personal characteristics, reinforcement of organizational culture and attitude along with paying attention to promoting their skills and occupational efficiency should be considered.