The purposes of this study were 1) to establish the concurrent validity of the universal goniometer and the fluid-based goniometer and 2) to determine the intertester reliability of these two instruments. A correlational study was performed in which two testers used the universal goniometer and the fluid-based goniometer in measuring elbow range of motion in 30 healthy subjects. The fluid-based goniometer had high intertester reliability (R = .92), and the standard goniometer had poor reliability (R = .53). The Pearson product-moment correlation between the two instruments was .83. A significant difference was shown between the standard goniometer and the fluid-based goniometer by the t test (t = 4.4, df = 28, p less than .05). The results support the use of the fluid-based goniometer between testers on elbow range of motion; however, the two instruments cannot be used interchangeably.