The purposes of this study were 1) to investigate school uniform image preferences and the uniform modifications of male and female high school students, and 2) to find the differences between male and female students in the uniform image preferences and uniform modifications. The subjects used for the study were 195 male and 201 female high school students. The uniform image preferences consisted of three factors: comfortable & simple, unique & individual, and intelligent & classic. The uniform modifications were measured by the modifications in jacket width, sleeve length, shoulder width, slacks(skirt) length, slacks(skirt) width, and slacks(skirt) waist length. The results showed that male and female students were different in regard to uniform image preference; male students preferred unique image than did female students in their school uniforms. In addition, male and female students differed concerning uniform modifications. Generally, female students modified uniforms more than did male students. Finally, the study compared male and female students in regard to the relationships between uniform image preferences and the uniform modifications. For male and female students, the unique image preference was significantly related to the modifications in different parts of uniform.