The mathematical skills possessed by students taking introductory biology courses were investigated. A list of 23 mathematical competencies was identified as part of the development of a 46-item multiple-choice test to measure the extent to which students possessed these competencies. The Biomathematics Skills Test (BST) was administered to students in introductory biology courses for science majors (BS-100) and nonmajors (BS-105). Although 804 students took the pretest, only 354 took the posttest. The relationships between the mathematical skills possessed by students at the beginning of the semester (measured by the BST) and 15 variables dealing with selected student characteristics were examined. Among the findings are those indicating that: males did significantly better than females in the BS-100 pretest but there were no significant sex differences in the case of BS-105; whites did significantly better than blacks on the pretest in both courses; and taking or not taking a mathematics or statistics course was not related to BST performance. BST scores and high school grade point average were found to be predictors of success in both courses. Scholastic Aptitude Test mathematics and verbal scores and age were also found to predict success in BS-100. These and other findings support the conclusion that the BST measures the mathematical skills needed in introductory college biology courses. (Author/JN)