The purpose of this study was to investigate teachers` perceptions of gender differences in students` mathematics and science learning ability. The sample included 289 elementary and secondary school gifted teachers. The teachers filled out the survey, asking their perceptions of gender differences in mathematics and science learning ability, as well as of the reasons of the differences. The results were as follows: 1) 65% of the teachers responded that gender differences existed in students` mathematics and science learning ability, 2) 63% of the teachers perceived that the differences began around higher elementary or middle school ages, 3) 57% of the teachers thought that gender differences existed in the high-achieving student group. Teachers perceived the reasons of differences were 1) differences in inborn ability, 2) the different expectation, and 3) the different ways of parental cares. Since teachers` perceptions of students` ability would impact teachers` attitudes on students, implications and suggestions were included in this article to provide teachers insights that promote students` better learning.