ABSTRACT The major purpose of the study was to determine Gender mathematics concepts' perception and its effects on academic performance of pupil's in selected Secondary schools of Ukwala Division, Ugenya District Kenya. The specific objectives of the study were to investigate the relationship between girl's attitude and performance in mathematics, Investigate the relationship between teachers' attitudes and girls' performance in chemistry, Determine the relationship between the curriculum and performance of girls in chemistry, Determine the relationship between over crowded classes and performance of girls in mathematics. The methods used for data collection were questionnaires to the pupils and interviews with the teachers. The study revealed that few girls enjoy mathematics because they think that mathematics. is hard and meant for boys who are clever. The study found out that teachers attitude towards girls performance in mathematics also affected their performance. The study also revealed that overcrowded classes contributed to poor performance of girls in mathematics. Finally the study revealed that the curriculum was too heavy for girls to handle and therefore performed poorly in mathematics. The government should construct facilities at school for mathematics teachers to teach in a conducive environment in order to aid the better performance of mathematics students in their schools. The government should have a policy in place that encourages the taking up of mathematics subject especially to the female students who at times think they are not good enough for the subject. The girl students should be encouraged to relate equally with there fellow boy students in all subjects regardless of whether it is mathematics. or not.