The introduction of computers in schools in the early 1980s was accompanied by high expectations about the potential of this new technology for improving student learning at school. In this century, expectation research outcomes, and new developments will be considered in relation to the prevailing educational computer applications, i.e., computer-assisted learning, word processing and logo. The investigator, who did his academic studies in Botany discipline, has genuine interest to know the effectiveness of Computer Assisted Instruction over Lecture Method for teaching Botany at Higher Secondary Level. The aim of the present investigation was to test the effectiveness of Computer Assisted Instruction over conventional Lecture Method for teaching Botany. For the present investigation the researcher adopted Experimental Method. The present study revealed that Computer Assisted Instruction is an effective tool for teaching Botany at Higher Secondary Level.