Academic achievement is very important in any educational setting, as it indicates the level of students' competence in respect of the academic content. This is obviously defined in terms of performance which represents the most understandable and regularly accepted pointer of performance in educational contexts (Ladipo & Gbotosho, 2015). Intelligence influences our ability on all level of intellectual tasks. Generally, people who are good at mathematics associate intelligence with it. Not everybody, but majority think on these lines. For them, being good at mathematics is an important criteria for being general intelligent. This study investigated the extent to which general intelligence determine the performance in mathematics among undergraduate students. The investigator used random sampling technique for selecting the sample from the population. The sample consists of 310 students studying undergraduate mathematics in Tirunelveli District, Tamil Nadu, India. Standardized tool namely Test of General Intelligence (TGI) for College Students by Misra and Pal was used and its reliability value was 0.81. The data collected were subjected to statistical techniques like t - test and F-test. Further analysis showed that majority of the undergraduate mathematics students had moderate level of general intelligence. Findings on relationships between general intelligence and performance of undergraduate mathematics students are positively correlated. The study recommended that the performance of study groups should be formed in the college to help in cooperative learning of outperformed students than male students. Since these groups will also help the weaker students to enhance the performance in their subjects.