The aim of this study is to determine the magnitude of cognitive dissonance present in a sample of female students at Umm Al Qura University, and clarifying the relationship between the cognitive dissonance and decision-making styles. It also aimed to identify differences between female students with high cognitive dissonance and those with low cognitive dissonance in decision-making styles. The study also aimed to unveil the most common styles for decision-making (intuitive, rational, spontaneous, dependent & avoidant) with the female students at Umm Al Qura University. The sample is composed of (263) subjects; all of them were female students at Umm Al-Qura University. Instruments used by the study were the cognitive dissonance scale (Cassel, Chow & Reiger, 2001) and the Scott and Bruce (Bruce Scott &, 1995) scale for decision-making styles. The most eminent result of the study, as of magnitude of cognitive dissonance, is that (40.3) of the total sample size reflect cognitive dissonance which suggests that the total cognitive dissonance present is below the average. The results of the study also showed a positive relationship of statistical function between the internal personal dimension in the cognitive dissonance scale and the overall and sub scores for the following decision-making styles (the intuitive, the spontaneous, & the avoidant style). The results also showed a negative relationship of statistical function between the cognitive dissonance in the internal personal dimension and the rational style. The results also showed a positive relation of statistical function between the cognitive dissonance in the external-social dimension (impersonal) and the scores of the following decision-making styles (intuitive style, the spontaneous style & the avoidant style). The results showed a negative relation of statistical function in the external dimension and the rational style. The results also showed a positive correlation of statistical function between the cognitive dissonance and in the external-social dimension and the independent style. The results showed the presence of statistical function differences between the subjects of high and low cognitive dissonance in the score of the spontaneous style dimension for the subjects of high cognitive dissonance. There also found statistical function differences between the subjects of high and low cognitive dissonance in the score of the avoidant style dimension for the subjects of high cognitive dissonance. (Contains 11 tables.)