Database Marketing is about the usage of customer database to improve marketing productivity of an organization, through proper customer acquisition, retention and development processes. The study examines the relationship between database marketing and customer loyalty of fast food firms in Port Harcourt, Nigeria. A total of 104 copies of questionnaires were distributed to the respondents. Ninety eighty (98) representing (94.2%) copies were accurately filled and useful, while the remaining six (6) representing (5.8%) copies were not properly filled and therefore not valid for the analysis. Spearman Rank order correlation coefficient was used to analyse and test the hypotheses. The study revealed that there is a positive and strong significant relationship between database marketing and customer loyalty of fast food firms in Port Harcourt, Nigeria .The study concludes that database marketing significantly increases the level of customer loyalty of fast food firms in Port Harcourt. The study further recommends that there is need for improvement in privacy policy of the fast-food firms and that third party involvement should be clearly communicated to consumers so that the overall perception of corporate policy can be significantly enhanced.