The study aimed at investigating the effect of using Brainstorming Strategy in teaching Islamic Education on the creative thinking and achievement of the tenth grade students in Sultanate of Oman. The researcher used the quasi-experimental design. A sample of fifty-six (56) students was randomly selected. Students were divided into two groups; an experimental group and a control group. Each group consisted of twenty-eight (28) students. The experimental group was taught by using the Brainstorming strategy while the control group was taught by using the traditional method. The content of teaching was the unit of the educational system in Islam studied by the tenth grade students (2004 2005). The researcher prepared the models to be taught using the Brainstorming strategy. He also prepared an achievement test. The test was pre-administered to control the variable of achievement. The researcher used the ability of creative thinking test prepared by Sayed Khair-Allah after measuring its validity and reliability The A-version was used to control the variable of creative thinking and the B-version was used as a posttest. The independent variables of the study were the Brainstorming strategy and the traditional method. The dependent variables were three abilities of creative thinking: fluency, flexibility and originality and achievement. The variables of sex, nationality, school environment, creative thinking and achievement were considered as control variables that might affect the internal validity of the study. After teaching the selected unit, the version (B) of the creative thinking test and the achievement test were administered. T-test was used to analyze the data. The results of the study showed that the experimental group outperformed the control group in the post-test of fluency, flexibility, originality and the total ability of creative thinking. Also, the experimental group outperformed the control group in the achievement test. .After analyzing the data, the researcher offered some recommendations and suggestions for further research