Use of the tibia as a lever to produce hip rotation for the purpose of measuring passive hip rotation range of motion (ROM) could result in inaccurate values if motion is allowed at the tibiofemoral joint (TFJ). The purpose of this study was to examine the effect of stabilizing the TFJ during measurement of prone hip rotation ROM in men and women. Passive hip rotation was measured in 20 unimpaired subjects (M = 10, F = 10) in two different stabilization conditions, with the TFJ stabilized and without the TFJ stabilized. A 2 x 2 analysis of variance was used to test for the effects of stabilization condition and gender on hip rotation measures. A significant interaction of gender and stabilization condition was obtained. Women displayed more hip rotation when the TFJ was not stabilized (M = 41.03°, SD = 6.53°) than when the TFJ was stabilized (M = 35.05°; SD = 5.12°). Men displayed no difference in ROM between the two stabilization conditions (not stabilized: M = 39.07°, SD = 4.87°; stabilized: M = 37.60°, SD = 5.12°). To avoid measurement error of hip rotation ROM, use of the tibia as a lever to produce passive hip rotation should be used with caution, particularly in women.