ABSTRACT The major purpose of the study was to determine Gender chemistry concepts' perception and its effects on academic performance of students in selected Secondary schools of Limuru Division, Kiambu-West District Kenya. The specific objectives of the study were to investigate the relationship between girl's attitude and performance in chemistry, Investigate the relationship between teachers' attitudes and girls' performance in chemistry, Determine the relationship between the curriculum and performance of girls in chemistry, Dete1mine the relationship between over crowded classes and performance of girls in chemistry. The methods used for data collection were questionnaires to the pupils and interviews with the teachers. The study revealed that few girls enjoy chemistry because they think that chemistry is hard and meant for boys who are clever. The study found out that teachers attitude towards girls performance in chemistry also affected there performance. The study also revealed that overcrowded classes contributed to poor performance of girls in chemistry. Finally the study revealed that the curriculum was too heavy for girls to handle and therefore performed poorly in chemistry. The government should construct facilities at school for chemistry teachers to teach in a conducive environment in order to aid the better performance of chemistry students in their schools. The government should have a policy in place that encourages the taking up of chemistry 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 chemistry or not.