This research aimed at Designing and Producing Instructional Software Computerized in Islamic Education and Measuring its Effectiveness on Achievement of Fourth Basic Grad Students. The sample of the study consisted of a group of Fourth Basic Grad Students in the academic year 2006/2007, and their numbers were (95) male and female students. The experimental group consisted of (15) male and (15) female students who were taught by using the computer; while the control group consisted of (15) male and (30) female students who were taught by the traditional method. The researcher used a multiple choice achievement test. Its content validity was checked by experts in education. Its reliability was checked by using KR-20.The results showed that there were statistically significant differences attributed to the effect of the teaching method in favor of the experimental group. The results also showed that there were no statistically significant differences attributed to gender. And there were statistically significant differences attributed to the interaction between gender and teaching method. A number of recommendations were presented on the basis of the finding of the research.