The purpose of this study was to explore the performance of three groups of students, gifted hearing students (GH), average-ability hearing students (AH), and deaf students (DF) on mathematical ability. The sample consisted of a total of 167 students (91 males and 76 females). Deaf students came from the Al-Amal School (an inclusive school for deaf students in Muscat, the capital of Oman) while average-ability hearing and gifted students came from public school students in Muscat in grades 6, 7, and 8. The tools of the study consisted of mathematical ability tests and Snigders-Oomen Non-verbal Intelligence (SON-R 5½-17). The researchers used the two-way ANOVA to answer the study questions. The results showed a significant main effect of the group (GH, AH, and DF). Post hoc analyses indicated that gifted students' level of mathematical ability was higher than AH and DF students. Deaf students scored the lowest among the three groups. The main effect of gender was not significant. The results of this study are discussed in relation to educational practices required to diminish the gap between hearing and deaf students in mathematical ability.