Aim: To define an insertion force (IF) threshold for ureteral damage with ureteral access sheaths (UASs) on an experimental ureteral orifice model. Materials and Methods: A specially designed water tank using 2 laparoscopic 5 mm ports and 2 different size (10 Fr and 8 Fr) sealing cap adaptors (SCA) as ureteral orifice model was used to perform the test. A 10–12 Fr UAS was fixed to a load cell and the IF was continuously recorded with a digital force gauge (DFS II, Chatillon, Ametek Test and Calibration Instruments, Largo, Florida, USA) during insertion. Each of the 11 experts in the field of endourology who participated performed 3 UAS insertions. The IF was recorded initially with 10 Fr followed by 8 Fr sealing cap orifice. On the final insertion, the orifice was obstructed, leaving a 5 cm length to insert the UAS. The experts were asked to ‘‘Stop at the point they feel there would be a ureteral damage and they would not proceed in real life’’. Results: Using 10 Fr SCA the max and average IF was 2.03 – 0.59 Newton (N) (range: 1.48–3.48) and 0.69 – 0.42 N (range: 0.04–1.54) while 8 Fr SCA showed a max and average IF of 5.72 – 1.00 N (range: 4.05–7.35) and 2.66 – 1.46 N (range: 0.37–5.79), respectively. Five of the experts, said they would stop proceeding when they reached above 5.1 N, 3 experts had IF < 5.1 and the other 3 said they would go with IFs of 5.88, 6.16 and 7.35 N when using SCA of 8 Fr. The highest load they would stop proceeding had max and average IF of 6.05 – 2.04 N (range: 2.53–10.74) and 2.66 – 1.46 N (range: 0.37–5.79), respectively. When excluding the 2 experts on the extreme of the IFs, the highest load to stop proceeding had max and average IF of 5.92 – 0.95 N (range: 5.04–7.65) and 2.86 – 1.37 N (range: 0.42– 4.97), respectively. Conclusion: The IF threshold for ureteral damage inserting UAS of the endourology experts is similar. Even though, IF is a subjective perception, experience indicates that ureteral damage may occur at 6.05 N. In-vivo measurement of UAS IF is awaited.