Abstract: This study aimed to investigate the effect of relationship marketing on customer loyalty in kaleh dairy products company using a survey method. The population of the research enterprise kaleh customers in Mazandaran province (one of the provinces of Iran) that according to the formula of unlimited kokaran only 270 members were selected and questionnaires were distributed among them. The SPSS software was used for data analysis. The results show that there is a significant positive relationship between trust, obligation, communication, conflict management and competence of Kaleh by loyalty of customers. Furthermore, the correlation coefficients of variables are denoted as 0.328, 0.480, 0.380, 0.442 and 0.534, respectively which indicates a strong positive relationship between independent variables and the dependent variable.