Abstract Background: The protocol established for taking Hand grip dynamometry measurements determines that the patient must be in a sitting position. this protocol cannot be applied due to the patient’s conditions in some cases, such as abdominal surgery, musculoskeletal spine or hip injuries. The purpuse was to determine the reproducibility and level of agreement between the Handgrip dynamometry in supine position with the elbow flexed or extended, and the one measured in the sitting position, for determining if these postures can be interchangeable depending on the patient’s condition. Methods: The design was a descriptive cross-sectional study. The population were apparently healthy students, who were young adults between 18 and 30 years of age. (N=201). Handgrip measurement was performed on both upper limbs in a sitting position with a flexed elbow, a supine position with elbow flexion, and a supine position with the elbow extended. Three handgrip measurements were taken for each upper limb in each posture. Results: Reproducibility was nearly perfect in all positions evaluated for both the upper right and left limbs (ICC 0.95-0.97). Regarding the level of agreement for the comparison between sitting and supine positions with a flexed elbow, an average difference of −0.406 was noted, and the upper and lower agreement limits were found to be 4.59 and −5.40, respectively. For supine position with an extended elbow and supine position with a flexed elbow, the average difference was −1.479, and the upper and lower agreement limits were 3.881 and −6.840, respectively. Conclusions: Taking into account the results achieved in this study, clinicians or researchers can choose any of the positions evaluated herein and obtain reliable results as long as the standardization process is followed. The criterion of choice could be the patient’s condition.