This study was carried out to determine the effect of computer simulation on students’ achievement and retention in Chemistry, four research questions were formulated to guide the study. The researchers reviewed some related literature. The study adopted a quasi experimental research design, one hundred and fifty (150) SS2 Chemistry students selected from four (4) schools were used. The reliability of the instrument was also tested. Mean and standard deviation were used to answer research questions while From the findings, it was observed that the use of computer simulation in teaching Chemistry had a significant effect on students’ achievement and retention among others. Conclusion, recommendations were made based on findings.