This study aimed to identify the effect of marketing information systems on the competitive advantage of pharmaceutical companies in Jordan. The study community and its sample were represented by all the employees in the Jordanian pharmaceutical companies which consisted of (400) employees who were chosen in a simple random manner. To achieve the objective of the study, the analytical descriptive method was used. After conducting the statistical analysis, the study concluded the following: There is a statistically significant relation between internal records, marketing research, marketing intelligence and competitive advantage in Jordanian pharmaceutical companies. Based on previous findings, the study recommends the following: The Company has to rely on many sources of marketing intelligence in the recruitment centers, employees and of the competing companies. Pharmaceutical companies should follow customer services through periodic reports on customer feedback, complaints and satisfaction with service performance.