<b>The Use of Problem Based Instruction Strategy PBIS in Gas Laws Class A Gender Academic Performance Difference</b> The study is an aspect of an unpublished Master thesis which employed quasi experimental design to investigate the gender academic performance difference in chemistry among senior secondary school students in Nigeria. The study sampled 165 students and used PBIS to teach the gas laws among the sampled students. The research used Gas Law Achievement Test GLAT and a researcher designed problem based instructional material as instruments. The data obtained were analyzed using the t test statistical analysis. Only one research question and one hypothesis guided the study. Finding reveals there was no significant difference between male and female students taught the gas laws using PBIS. The study has implications for the teaching and learning of chemistry. problem based instruction, gas law, academic performance, chemistry curriculum 458-464 Issue-4 Volume-1 Popoola Rachael Adewumi | Olorundare, A. Solomon