Background/Objective: For effective bystander cardiopulmonary resuscitation (CPR), retention of CPR skills after the training is central. The objective of this study was to find out how much of the CPR skills a group of Nigerian secondary school students would retain six weeks after their first exposure to the conventional CPR training. Materials and Methods: It was a quasi-experimental study design with participants drawn from both private and public secondary schools in Obio/Akpor Local Government Area in Port Harcourt, Rivers State, Nigeria. The initial cohort (stage I) involved 400 participants from senior secondary school 1 and 2 (SS1) and SS2) when their baseline CPR skills were assessed. The same group was assessed again immediately after the CPR training (stage II) and six weeks post training (stage III). The final cohort involved in both stages I, II and III of the study was 322 exposed to both class room teachings and the practical hands-on sessions using manikins in line with the American Heart Association (AHA) guidelines. The data was analyzed using descriptive statistics, ANOVA and t-test. Results: The CPR skills retained by the participants six weeks after their exposure to the training were found statistically (P < 0.05) significant. Neither age nor gender had any significant influence on their CPR skills. Conclusions: The Nigerian secondary school students can learn and retain CPR skills and could serve as effective bystanders CPR providers in emergency situations. Incorporation of the teaching of CPR into Nigerian secondary school curricula is recommended.