The purpose of this study were to determine 1) the reliability of the Orthoranger for assessing active lower extremity joint range of motion, 2) specific methods for applying the Orthoranger, and 3) whether a correlation exists between the measurements obtained with the Orthoranger and those obtained with a standard goniometer. Ten men and 10 women, mean ages 28.3 +/- 5.1 and 30.0 +/- 10.1 years, respectively, participated in the study. Random selection was used to determine testing sequences. The Orthoranger and the goniometer were used to measure each joint three times during the five sessions. Results indicated that both instruments were reliable for assessing active lower extremity joint ROM. The goniometer showed greater intraclass correlations and confidence levels for all movements except hip lateral rotation, which demonstrated a higher intraclass correlation for the Orthoranger. In addition, all motions except hip adduction and knee extension demonstrated a positive relationship between instruments. Compared with a manual goniometer, the added costs for purchase and use of the Orthoranger appear to be unnecessary until such time that factors enhancing its inherent reliability are identified.