The purpose of this study was to examine intratester reliability of a test designed to measure tightness in the hamstring muscles. The test measures the angle of knee flexion with a pendulum goniometer after active knee extension with the hip stabilized at 90 degrees flexion. The angle of knee flexion represents hamstring tightness. After an instruction session for the subjects, the hamstring muscle tightness of both extremities of 15 men was measured during test and retest sessions. The reliability coefficients for test and retest measurements were .99 for the left extremity and .99 for the right extremity. High reliability resulted from strict body stabilization methods, a well-defined end point of motion, and accurate instrument placement. If conducted properly, the test should provide therapists with an objective and reliable tool for measuring hamstring muscle tightness.