The study investigated Effect of Reflective Instructional Strategy on students’ performance in Cell-Physiology Concepts among Senior Secondary Students in Zaria. Quasi-experimental pretest, post test control group design. The population comprised of one thousand two hundred and twenty five Biology SS11 students from 11 public Senior Secondary Schools in Zaria metropolis. A sample of 137 students from two schools was randomly selected. The study involves two groups- experimental and a control group. The experimental group was taught Cell Physiology using Reflective Instructional Strategy while the control group was exposed to the same concept using Conventional Method. One instrument was used for data collection Namely Cell- Physiology Performance Test. The instrument was duly validated and have reliability coefficient of 0.87, using Pearson Product Moment Correlation statistic. Two research questions and two null hypotheses were formulated and answered using Mean and Standard deviation statistics and Independent Samples t-test at alpha 0.05 level of significance. The major findings reveals a significant difference between mean academic performance scores in favor of the experimental group. Based on the findings, it was recommended among others, that workshops, seminars and conferences should be organised for Biology teachers on the use of Reflective Instructional among secondary schools in Zaria metropolis