400 urinary stone patients were treated with the electromagnetic lithotriptor Siemens 'Lithostar': 66.3% had renal stones and 33.7% had ureteral stones. Ninety percent of the treatments were performed under intravenous sedation only: 14.5% of the patients had more than one session. After 3 months more than 80% of the patients with a single stone smaller than 1.5 cm and 46% of the patients with stones larger than 2.5 cm were 'stone-free'.