Background: The need for training of schoolchildren on cardiopulmonary resuscitation (CPR) as potential bystander CPR providers is growing globally but Nigeria is still behind and lacks basic necessary data. Purpose: The purpose of this study was to investigate the effects of age, gender and school class on CPR skills of Nigerian secondary school students. Methods: Using a pretest-posttest quasi experimental study design, 322 senior secondary school students recruited from four schools in Obio/Akpor Local Government Area of Rivers State, South- South, Nigeria. The cohort was assessed on CPR skills before CPR training, immediately after the training and six weeks later for CPR skills retention. Descriptive, parametric and non-parametric statistics were used to analyze the data with statistical significance set at P < 0.05. Results: The three null hypotheses were all accepted as both age, gender and school class were found not to statistically have any influence on the CPR skills of the participants (P > 0.05). Conclusion/Recommendation: If our current findings are confirmed after further research work, CPR training in our schools should be encouraged for incorporation into our schools' curricula focusing on the senior secondary school students.