The next generation of life science professionals will require far more quantitative skills than prior generations. Calculus is important for understanding dynamical systems in biology and, therefore, is often a required course for life science students. However, many life science students do not understand the utility value of mathematics to biology. Therefore, according to expectancy-value theory, life science students may experience lower motivation, which can impact their performance in a calculus course. This study examines how two different biocalculus courses, which integrated calculus and biological concepts and successfully halved the rates of students earning a D, F, or withdrawing (DFW), affected life science students' utility value, interest, and overall attitudes toward mathematics. Using pre and post surveys, we found that students' interest in mathematics increased by the end of the semester, and they demonstrated a more sophisticated understanding of how mathematics is used in biology. Students whose attitudes toward mathematics improved primarily attributed these changes to a better understanding of the utility of mathematics to biology, feelings of competence in mathematics, or rapport with the instructor. Thus, communicating the utility value of mathematics to biology through integrated mathematics-biology courses can contribute to improved attitudes toward mathematics that can impact students' motivation and performance.