The purpose of this research was to analyze and explain the effect of organizational citizenship behavior, locus of control and on the performance of PERUMDAM Tirta Satria Banyumas employees. This research is a quantitative research using a questionnaire of 160 respondents to the employees of PERUMDAM Tirta Satria Banyumas. The sampling technique used an accidental sampling method. Data analysis used multiple linear regression and coefficient of determination test. The results of the study indicate that organizational citizenship behavior, locus of control and perceived organizational support has a significant effect on employee performance.