This study aimed to investigate the effectiveness of teaching Mathematics by using 7E's Learning Cycle strategy in immediate and delayed achievement and retention among Preparatory Year students at King Saud University (KSU)--Saudi Arabia, in comparison with the traditional method. The study sample consisted of (73) Preparatory Year students at KSU who were divided into two groups: the first group consisted of (35) students, who studied mathematics by using the 7E's Learning Cycle; and the second group consisted of (38) students, who studied the same content by using the traditional method. ANCOVA results analysis of the students' scores on the mathematics achievement tests indicated that the 7E's Learning Cycle is more effective than the traditional method on the immediate and delayed mathematical concepts achievement. Also, the results analysis of paired-samples t-test indicated that the 7E's Learning Cycle has a positive longitudinal effect on retention among the Preparatory Year students at KSU, while the traditional method is not effective in this aim.