The purpose of the study was to determine the extent supervision of instruction enhances quality assurance in biology teaching and learning in secondary schools in Enugu East LGA, Enugu State. Two research questions and two hypotheses guided the study. Descriptive research design was used for the study, the study population was 169 biology teachers – 124 urban and 45 rural teachers. The entire population was used as sample because population was small. Questionnaire was used for data collection. Its cronbach Alpha reliability index was 0.68. Mean and standard deviation were used to answer the research questions. t-test was used in testing the hypotheses. The results that both urban and rural biology teachers accept that supervision of instruction is (a) essential and (b) enhances quality assurance in biology teaching and learning in secondary schools. There is no significant difference between the mean scores of urban and rural biology teachers on the extent to which supervision of instruction is (a) essential (b)enhances quality assurance in biology teaching and learning in Enugu East LAG secondary schools It was recommended among others that PPSMB should continue to intensify the use of supervision of instruction in enhancing quality assurance in secondary schools.