Background Colorectal cancer is one of the most common internal malignancies affecting Australians, and colonoscopy is widely accepted as a part of comprehensive large bowel assessment. Different specialties perform colonoscopies, most commonly general surgeons and gastroenterologists. Analysing performance outcomes against benchmarks allows insight into inter-specialty differences and enables the improvement of overall service provision and quality. Methods We performed a retrospective single-centre cohort study on 2086 patients undergoing colonoscopies by seven surgeons (S) and nine gastroenterologists (G) between July 2021 and June 2023. Primary outcomes were comparative caecal intubation rates (CIR), photo documentation rates (PDR), documented withdrawal rates (DWR), withdrawal times (WT), and adenoma detection rates (ADR). Secondary outcomes characterised adenoma frequency, optimal WT, and indications for colonoscopies. Results We found significant differences in CIR (S: 94.9%, 990/1043; G: 99%, 1033/1043, P<0.01), PDR (S: 95.9%, 949/990; G: 99.1%, 1024/1033, P<0.01), DWR (S: 17.4%, 181/1043; G: 87.3%, 911/1043, P<0.01), WT >6 minutes (S: 82.3%, 149/181; G: 97.8%, 891/911, P<0.01), and ADR (S: 37.9%, 193/509; G: 59.7%, 421/705, P<0.01). Subgroup analysis revealed adenoma frequency peaked at 50-70 years old and optimal WT was ≥9 minutes. We demonstrated surgeons mainly perform colonoscopies for diverticulitis surveillance, abnormal imaging, post-cancer resections, and rectal bleeding, but gastroenterologists predominantly investigate bowel symptoms, polyp surveillance, positive faecal occult blood test, and anaemia. Conclusion Despite both specialties surpassing national standards in CIR and ADR, there were significant differences in performance indicators. We believe ADR differences could be explained by different indications specialties perform colonoscopies for. Increasing WT ≥9 minutes could improve ADR, and education on the usage of withdrawal timer on endoscopes will improve DWR., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. St. John of God Health Care Human Research Ethics Committee issued approval 2080. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Tan et al.)