Purpose – The purpose of this paper is to analyse the possible influence of internal marketing (represented by internal market orientation (IMO)) on external customer outcomes (perceived service quality and customer satisfaction) through the mediating role of employees’ attitudes (job satisfaction, trust and commitment) that comprise relationship quality. Design/methodology/approach – The authors employ a dyadic methodology, with 244 dyads (employee-the average of his/her three patients) at the outpatient services of five Spanish hospitals. The authors use structural equation modelling (EQS6.1) to test the relationships of the model. Findings – The results corroborate the hypotheses proposed in the model, with the exception of the influence of IMO on commitment. Significant differences in some relationships, depending on the experience of the employee, are also corroborated. Research limitations/implications – The paper analyses one service activity in the same region. Only perceptual data are used to measure the variables of the model. Practical implications – Service companies should consider IMO because it contributes to creating an excellent customer experience. Furthermore, managers should bear in mind their employees’ needs when taking decisions. Originality/value – This paper contributes to the literature by demonstrating, for the first time, the mediating role of relationship quality in the influence of IMO on external outcomes. It is also the first paper in internal marketing to analyse the differences in the consequences of IMO according to employee tenure.