The present study was undertaken to compare the effects of Computer Assisted Instruction (CAI) on the achievement of Junior High School (J.H.S) students in Pre-Technical skills. The study compared the student?s achievements through two modes of instruction, the CAI and the traditional methods of instruction. Two schools which can be matched by intellectual capabilities and also had well equipped computer laboratories were assigned to the CAI and the Traditional groups. The study involved 59 students from two schools in Kumasi Metropolis. Twenty eight of the students formed the CAI group while 31formed the traditional group. The method used for the study was the quasi-experimental design. The groups received CAI and traditional instructions respectively, their level of achievements were measured by Pretest and Posttest achievement test. The data (pretest and posttest scores) obtained were analysed with Analysis of Covariance (ANCOVA) using Statistical Package for Social Science (SPSS). The key findings of the experiment revealed that students of the CAI group using the CAI performed better than students of the traditional method of instruction group (Traditional group).