<div><p>ABSTRACT Objective: To determine the reliability of two classification methods for wound hematoma after total hip replacement. Methods: This prospective cohort study was conducted on patients who underwent total hip replacement for hip osteoarthritis between May 2014 and April 2015. Epidemiological, surgical, and functional data were assessed. Two experienced hip surgeons evaluated 75 pictures of wounds taken 24 hours after surgery. Both evaluators performed the analysis twice, with a 6-week interval between the two analyses. The subjective classification was divided into four different categories describing the hematoma: absent, mild, moderate, and severe. The objective classification was derived from mathematical calculation of the area of the hematoma using a grid superimposed on a picture of the wound. Results: The subjective classification demonstrated an intra-rater agreement of more than 70%, while kappa values showed poor to moderate inter-rater reliability. The objective classification based on mathematical measurements of the hematoma area was more reliable, with good to excellent intra- and inter-rater reliability. Conclusion: The objective classification demonstrated higher intra- and inter-rater reliability. The classification methods used in this study could serve as a useful instrument for orthopedic surgeons, researchers, and health care providers when assessing wound hematomas after total hip replacement. Level of Evidence II; Development of diagnostic criteria on consecutive patients (with universally applied reference ‘‘gold’’ standard).</p></div>