Mathematics is an important component of school education. It teaches us to think logically. But learning this subject is not easy due to its abstract nature. Students find it difficult to learn mathematics due to a lack of interest in the subject. Nowadays schools give importance to grades and marks rather than teaching the subject interestingly. The present study was conducted to determine high school student's interest in mathematics and their cognitive strategies concerning gender. The sample consisted of 738 students studying in 9th standard and they are selected from 18 schools of Thanjavur educational district using the purposive sampling technique. Data were analyzed using t-test. The findings showed that a significant difference could be seen in showing interest in learning the subject and applying cognitive strategies based on gender. Females showed more interest in the subject and their cognitive strategies are better than males.