Low students’ learning outcomes and retention are among the problems in learning. An innovation in the learning process is thus needed to solve the problems. The effect of Preview, Question, Read, Reflect, Recite, Review and Read (PQ4R) learning model integrated with a mnemonic-based module is one of the useful alternatives to overcome the problems. This study aims to address the question on how the integration between the PQ4R learning model and a mnemonic-based module affects the students’ learning outcomes and retention. This study used an experimental method with a Quasi-Experimental design.The research subjects were 124 students who were selected purposively from four parallel classes in one high school in Banda Aceh, Indonesia, from a total population of 16 public high schools in Banda Aceh. The subjects were divided into two groups, namely the experimental and control group; each of which consisted of 62 students. In the experimental group, the PQ4R model combined with mnemonic-based modules was used, while in the control group, PQ4R with a conventional learning module was applied. The measured parameters were the students’ learning outcomes and retention. To examine the significance of learning outcomes between the experimental and control group, the Analysis of Covariance (ANCOVA) statistical test was employed. The data for retention were obtained from the results of posttest, retention test-1 (retest-1) and retention test-2 (retest-2). The retention was analyzed by using a recognition method. The results showed that there is a significant difference between the learning outcomes of the students in the experimental class and those of the students in the control class. The experimental class has a better retention rate compared to that of the control class. Thus, the application of the PQ4R learning model combined with a mnemonic based module can positively contribute to improving students’ learning outcomes and retention.