Purpose: To determine the relationship between iliotibial band (ITB) length and the presence of patellofemoral pain syndrome (PFPS), compare the difference in ITB length between the painful knee and the non-painful knee in subjects with unilateral PFPS, determine the test-retest reliability, standard error of measurement, and minimal detectable change (MDC) of the Ober test and modified Thomas test, and explore the relationship between the Ober test and the modified Thomas test in measuring ITB length. Subjects: Forty-eight subjects were recruited (PFPS group n=24, control group n=24) from three different outpatient physical therapy clinics. Methods: The Ober test and modified Thomas test was conducted on both legs of each subject to determine ITB length with the use of a digital inclinometer. Examiners were blinded to group assignment and an independent observer recorded all the results. Results: The mean values for hip adduction during the Ober test was 7.2 degrees in the control group and 2.3 degrees in the PFPS group. One way ANOVA revealed a significant difference between groups (p= .011). There were no differences in ITB length comparing the painful knee to the non-painful knee for both the Ober test and modified Thomas test. The ICC values calculated for the test-retest reliability were .95 for the Ober test and .86 for the modified Thomas test. Pearson correlational analysis revealed a weak negative correlation (r=-.40, p=.005) between the Ober test and modified Thomas test on the left side and no correlation on the right side. Discussion and Conclusion: The Ober test is better at distinguishing between a PFPS group and a control group than the modified Thomas test supporting the clinical utility of the Ober test. The use of a digital inclinometer for both the Ober test and modified Thomas test appears to be a reliable method for the measurement of ITB length. However, given the lack of relationship found between the two tests, the two examination procedures should not be used interchangeably for the measurement of ITB length.