Nowadays, commercial enterprises confront a clientele increasingly informed and therefore demanding and volatile, especially in the telecoms sector in Morocco. For that purpose, the customer capital becomes a central concern of these companies. Furthermore, the solution that seems most effective to deal with these challenges is to set up a relational dimension. In order to verify the impact of the relational dimension of marketing on customer loyalty, an empirical study was conducted with 138 customers of Moroccan telecom operators (Maroc Telecom, Meditel and Wana Corporate). The results of this study confirm that all elements of relational marketing have a positive and significant effect statistically on customer loyalty. Found and develop a customer capital is the aim of any business. To this end, Moroccan telecom operators must establish trust with customers, to notify their customers of any information deemed useful and satisfy their expectations while being close to the customer as well as personalizing the customer-company relationship.