<h3>Study Objective</h3> We aim to assess the performance of the "2021 AAGL Endometriosis Classification" compared with revised American Society of Reproductive Medicine (rASRM), Ultrasound Based Endometriosis Staging System (UBESS) and modified Ultrasound Based Endometriosis Staging System (mUBESS) to predict AAGL levels of surgical complexity. <h3>Design</h3> Multicenter retrospective diagnostic accuracy study. <h3>Setting</h3> 2 gyneacology units in metropolitan Sydney, Australia. <h3>Patients or Participants</h3> Patients with suspected endometriosis who underwent laparoscopy between January 2016 and October 2021 (n=272). <h3>Interventions</h3> Database of patients with comprehensive surgical data including location & severity of endometriosis & surgical procedure performed was analysed. AAGL surgical complexity level (A to D) was pre-determined by consensus between three observers. For the three stage UBESS to be compared with the four levels of AAGL surgical complexity, levels B and C were merged. rASRM stage 1, 2, 3 and 4 predicted AAGL level A, B, C and D, respectively. UBESS stage 1, 2 and 3 predicted AAGL level A, B/C and D, respectively. mUBESS stage 1, 2, 3 and 4 predicted AAGL level A, B, C and D, respectively. The performance of all staging systems was assessed using kappa, accuracy, sensitivity, specificity, positive predictive value (PPV,) negative predictive value (NPV) and likelihood ratios. <h3>Measurements and Main Results</h3> Across all diagnostic accuracy measurements there was no clear difference between the four staging tools. For overall comparison, kappa/weighted kappa scores respectively were: For AAGL 0.42 & 0.55, for rASRM 0.41 & 0.55, for UBESS 0.44 & 0.57 and for mUBESS 0.47 & 0.58. <h3>Conclusion</h3> Across all tools, there was good concordance for mild and severe disease to predict surgical skill level. For intermediate disease there was weak concordance. There was no clearly superior tool.