AIM: Small stone fragments (NSRF) may be observed after mini-invasive lithotripsy. A 3-components herbal extract drug was tested in young patients presenting NSRF to assess efficacy, safety and tolerability. MATERIAL AND METHODS: Patients aged 6-18 years, treated by endo-urological procedures in 5-year period, were randomly divided in 2 groups. Group A received a 3-components phytotherapic composed of Herniaria hirsuta and Peumus boldus plus water oral intake for 12 days/month in 3 months. Group B had no adjuvant phytotherapy. Group A and B were divided in 2 subgroups, according to persistence of NSRF. Patients were evaluated after the endo-urological procedure (Time 0), at 3-months therapy (Time 1) and after 3-months follow-up (Time 2). Persistence or development of new micro-lithiasis, adverse effects and urological check were registered. RESULTS: Thirty-four patients were enrolled (Group A=15, Group B=19). Two patients were excluded. In Group A, 6 patients were stone free at Time 0 and had no recurrence, while 7 patients (53.8%) had NSRF at Time 0, reduced to 3 (23.0%) and to 2 (15.4%) at Time 1 and 2 respectively. In Group B, 11 patients (57.9%) presented NSRF at Time 0, reduced to 8 (42.1%) and 7 (36.8%) at Time 1 and 2. The difference was significant (Time 1 p=0.006, Time 2 p=0.009). No adverse effects were reported. DISCUSSION AND CONCLUSIONS: The drug was effective in preventing new stones development and reducing significantly stone fragments persisting after endo-urological lithotripsy in children, with optimal tolerability and no adverse effects.