Objective The objective of the article is to compare the results of using new screwed Amplatz sheath with results of the conventional Amplatz sheath regarding success and complications during percutaneous nephrolithotomy. Methods 100 patients aged more than 18 years with renal calculi more than 2 cm with guy's score 1 from December 2018 till July 2020 were randomly stratified by closed envelope in group A (50 patients) with using conventional sheath and group B (50 patients) with new screwed sheath. We exclude morbid obese patients and patients with contraindication for PNL. Results There were no significant differences between both groups regarding patients demographic and stone demographic. Operative time and fluoroscopy time were significantly lower in group B rather than group A. Tract stability was in favor of group B as no tract loss recorded while in group A, 5 cases were recorded. In overall complications there were no significant differences between both groups. Bleeding was higher in group A (14%) than in group B (4%), but it was not statistically significant. Success rates were 78% for group A and 88% for group B but it was not statistically significant. Conclusion The screwed Amplatz sheath had showed less operative and fluoroscopy time. Also it enables urologists to have stable PNL tract. So it may be a promising tool to make PNL easier with higher success rate and lower complications. Supplementary Information The online version contains supplementary material available at 10.1007/s00345-021-03806-2.