Context: The evaluation of the wrist strength and proprioception gives clinicians and researchers information about effectiveness of their rehabilitation protocol or helps diagnosis of various neuromuscular and somatosensorial disorders. Isokinetic dynamometers are considered the gold standard for these evaluations. However, the studies about test–retest reliability of isokinetic dynamometer are inadequate. Objective: The purpose of this study was to determine the test–retest reliability of isokinetic wrist strength and proprioception measurements using the Cybex isokinetic dynamometer. Design: Test–retest reliability study. Setting: University laboratory. Participants: Thirty participants were enrolled (age 23.2 [2.8] y, height 171.1  cm, weight 66.6 [11.6] kg) in this study. Intervention: Cybex isokinetic dynamometer was used for strength and proprioception measurements. Main Outcome Measures: Concentric flexion–extension strength test was performed at 90°/s angular velocity, and eccentric flexion–extension strength test was performed at 60°/s angular velocity. The proprioception of the wrist was assessed via active joint position sense. The 30° extension of the wrist, which is accepted as the functional position of the wrist, was selected as the targeted angle. The intraclass correlation coefficient (ICC2,1) method was used for test–retest analysis (P < .05). Results: The active joint position sense measurements of dominant (ICC2,1: .821) and nondominant (ICC2,1: .763) sides were found to have good test–retest reliability. Furthermore, with the exception of dominant eccentric extension strength (moderate reliability) (ICC2,1: .733), eccentric and concentric flexion (dominant: ICC2,1 = .890–.844; nondominant: ICC2,1 = .800–.898, respectively), and extension (dominant: ICC2,1 = .791 [concentric], nondominant: ICC2,1 = .791–.818, respectively) strength measurements of both sides were found to have good reliability. Conclusions: This study shows that the Cybex isokinetic dynamometer is a reliable method for measuring wrist strength and proprioception. Isokinetic dynamometers can be used clinically for diagnosis or rehabilitation in studies which contain wrist proprioception or strength measurements.