Purpose - The purpose of this paper is to describe an improvement project and its effects on decreasing the time from diagnosis to treatment for patients with kidney stones and to reduce the negative effects related to untreated stones at one hospital in western Sweden. Design/methodology/approach - A quantitative descriptive study based on Nolan's improvement model was used. The quality improvement effects were evaluated using statistical process control. Findings - Extracorporeal shock wave lithotripsy treatment's positive effects within 48 hours were described as efficiency (decreased waiting time) from diagnosis to treatment, even if a re-treatment was necessary. The results also showed a reduction in the usage of percutaneous nephropyelostomies as a treatment option. Research limitations/implications - This study includes data from one department at one hospital in one country. Comparative data include the time from acute radiological examination to final treatment but not total re-treatments, complications or time to up following radiological examination. However, the study was performed over one year and analyzed data from medical records in a systematic way. Practical implications - This study may inspire measuring and developing routines from diagnosis to treatment for patients who are transferred within different departments at one hospital. Social implications - By measuring the working process, resource use within a healthcare organization could be visualized. Planning and co-operation at different managerial levels are key factors for success when improvement projects are performed. Originality/value - Studies in improvement projects considering ureteral or kidney stones are generally lacking; thus, this study is important for improving the care of patients with this diagnose.