It has been well documented that fitness knowledge can help students regularly engage in more physical activity, and fitness knowledge instruction and testing should be vital components of overall physical education programs. The purpose of the study was to examine 9th graders' fitness knowledge in order to provide baseline data to investigate the relationship between fitness knowledge and corresponding behaviors of students. Ninth graders (n = 185) from three high schools in a metropolitan area school district participated in the study. FitSmart, a standardized computer-based fitness knowledge test for high school students, which has been sponsored by the American Alliance of Health, Physical Education, Recreation and Dance, was used to collect data concerning students' fitness knowledge. The test consists of 50 weighted multiple choice items, measuring six subdomain components: concepts of fitness (CF), scientific principles of exercise (SPE), components of physical fitness (CPF), effects of exercise on chronic disease risk factors (CDR), exercise prescription (EP), and nutrition, injury prevention, and consumer issues (NIPCI). An overall criterion score of 50 is the cut-off score for meeting the Healthy Fitness Knowledge Zone. For subdomain components: CF: good = 12, better => 20; SPE: good = 11-19, better =>20; CPF: good = 18-27, better =>28; CDR: good =8-13; Better =>14; EP: good=1-2 better =>2; and NIPCI: good = 9-14, better =>15. There are two versions of the test and Form 1 was used in the project. Means and standard deviations of the overall and the six subdomain scores were computed. The recommended cut-off scores were used to evaluate students' mastery of fitness knowledge. The overall mean score of 40.48 (SD=7.25) and the six subdomain scores (i.e., CF=7.16, SD=3.99; SPE=6.95, SD=3.49; CPF=9.75, SD= 4.44; CDR=4.57, SD=2.62; EP=.74, SD=1.17; NIPCI=5.16, SD=3.42) were less than the scores meeting the Healthy Fitness Knowledge Zone. The data from the study suggested that more efforts are needed to ensure that students master fundamental fitness knowledge.Keyword(s): assessment, high school issues, measurement/evaluation