Analysis of our experience in 'in situ' ambulatory shockwave extracorporeal lithofragmentation of ureteral stones in 104 patients seen in the Lithotrity Unit, Urology Service, Fundación "Jiménez Díaz". Using Modulith SL 20, a third generation lithotripter, 'in situ' disintegration was achieved in 82.69% of cases, 51.92% of which were fragmented in a single lithotrity session. As a first choice, no ureteral handling was used in any of the patients prior to lithotrity. In 9.62% of patients it was necessary to place a 'double J' by-pass catheter, due to the disease presenting with a septic picture. The patient's position was either dorsal or ventral decubitus depending on the lithiatic site, while location and focusing of the stones was done radiologically. All patients were treated ambulatory without hospitalization. Only 18% was given oral or i.v. anaesthesia. Fursemide 40 mg was administered to all patients shortly before starting the session. Each patient received an average of 3,200 shockwaves per session (14-18 Kv, average 16 Kv). Haematuria was the single and modest side effect that happened during the 24 hours following lithofragmentation in 30% of patients, while 20% reported slight discomfort at the time of eliminating the gritted stones. We conclude stating that 'in situ' shockwave extracorporeal lithotrity of ureteral stones with Modulith SL 20 allows for elective disintegration of ureteral stones in whatever location they are found, due to the patient's easy positioning. The simple location and focusing of ureteral stones has allowed us to treat and solve some cases of ureteral lithiasis at the precise moment of the nephritic colic painful emergency, thus speeding up and facilitating the resolution of the condition. Our results and our strategy imply a new change of direction in the management of these lithiasis, as opposed to the well established and historical doctrines in existence regarding stones with ureteral location.