Nowadays, by the daily expansion of service industries, the subjects of service
marketing and service quality have been converted into vital issues for all
organizations. Abundant attempt of organizations in this area is a clear
evidence of this claim. In the past years, organizations have tried to provide
high quality service and better external customer satisfaction through external
marketing concepts and attitudes of external marketing. One of the important
specifications of services is the employees 'direct interactions with customers
and the determinant role of their customer-orientation behaviors in contact
with customers. Therefore, to gain superior service quality thus external
customers ’satisfaction, we should have employees (internal customers) who
are obligor to the company's goals and visions. They should also have
customer-orientation behaviors. Nowadays, with the introducing of internal
marketing concept, the importance of organization's internal customers
(employees) in the success of external marketing plans has become more
obvious. Researches have indicated that there is a close interaction and
relationship between internal and external marketings. According by, the
present research was conducted to identify the effect of internal marketing's
effect on organizational citizenship behaviors and quality of services. The
research methodology was survey - correlation based on the structural equationsmodel. Using conceptual model (path analysis), the obtained results indicated
that internal marketing effect in Great Tehran Gas Company (GTGC) has
increased organizational citizenship behaviors of the employees as well as the
quality of services.