Objective: After extracorporeal shock wave lithotripsy (ESWL), residual fragments (RF) 4 mm or less are usually considered as clinically insignificant. We retrospectively reviewed the natural history and clinical significance of 97 noninfected and isolated RF (4 mm or less) observed 3 months after the last ESWL session on renal tomography.Patients and Methods: They represented 83 among 1,216 patients treated by ESWL over a 9–year period (1989–1997). These RF were mostly localized in the inferior calyx (62%). Median follow–up was 40.6 months (range: 7–96 months). Renal tomography was always performed at the end of follow–up.Results: Stone–free status, or a decreased, stable or increased amount of residual stone occurred in 27 (33%), 1 (1%), 24 (29%) and 31 (37%) of the 83 patients, respectively. During this study, 18 patients (22%) were proposed for a complementary treatment related to a size increase of the residual fragments (13 ESWL, 1 retrograde endoscopy, 3 percutaneous nephrolithotomy, and 1 polar inferior nephrectomy).Conclusion: The term clinically insignificant should not be employed to describe RF after ESWL. Efforts should be performed to obtain true stone–free status after ESWL.