The purpose of this study was to investigate the effect of computer simulation in probability teaching on probabilistic thinking of eleven grade students in the pure Mathematics course and on their attitudes toward probabilities. The study sample consisted of (55) students from Saada Female Generai Education school (10-12).im Dofar region (the experimental group = 27, the control group=28). For the purpose of this study, the researcher used two scalės: "a Probabilistic thiriking test consisting of (13) questions and a scale of ::.students' attitudes toward probability consisting of (21) items. The results indicated that there were statistically no significant differences in the probabilistic test. There were also statistically significant differences in the students attitudes in favor of the experimental group."