Introduction: One of the nursing challenges is nurses' motivation and job satisfaction. Applying motivational theories by nurse managers might be an effective strategy. The aim of this study was to determine the effect of using designed program based on “Expectancy Theory” by head nurses on nurses' job satisfaction.

Materials  and Methods: This study was a quasi-experimental study that was done in two hospitals in Zanjan providence. Data were gathered by "Nurses' Job Satisfaction Questionnaire". In this study, internal consistency reliability (Cronbach's alpha) of the questionnaire was measured (α=0.9). Method of sampling was census and nurses were selected in the case group(n=20) and nurses in the control group (n 19). They were matched in two groups. The applied program was based on “Expectancy Theory” that implemented in case group for 6 months. Data were analysed by Mann-Whitney, Wilcoxon Chi-Square and SPSS/16 used.

Findings: The nurses in two groups were matched (P>0.05). Job satisfaction before and after in two groups did not different significantly, it showed by using Wilcoxon test (P>0.05). But findings showed that nurses' job satisfaction in case group increased 7%.

 Conclusion: The program based on “Expectancy Motivational Theory” had clearly implementation steps for applying this theory that it would be practical guide for nurse managers. Use of this theory for improving nurses' job satisfaction is suggested.