ObjectivesTo elucidate the significance of intrarenal reflux.MethodsWe retrospectively analyzed 276 patients (age <5 years) with grade III to V vesicoureteral reflux. They were divided into two groups: 55 patients with intrarenal reflux and 221 patients without intrarenal reflux (control group). All patients received low‐dose antibiotic prophylaxis.ResultsThe most common initial presentation in both groups was febrile urinary tract infection. On dimercaptosuccinic acid scan, the rate of decreased differential renal function (<40%) was significantly higher in the intrarenal reflux group than in the control group (51% vs 33%, P < 0.05). Breakthrough urinary tract infections were observed in 26 patients (47%) in the intrarenal reflux group and 61 patients (28%) in the control group (P < 0.01). There was no statistically significant difference regarding spontaneous resolution of reflux, which occurred in nine patients (16%) in the intrarenal reflux group and 32 patients (14%) in the control group. Surgical treatment was selected more often in the intrarenal reflux group (P < 0.05) because of the high incidence of breakthrough urinary tract infection.ConclusionsThe rate of spontaneous resolution of high‐grade vesicoureteral reflux is similar between patients with and without intrarenal reflux. However, those with intrarenal reflux present are more likely to present a decreased differential renal function and breakthrough urinary tract infections. Consequently, surgical treatment is considered more frequently in cases with intrarenal reflux. Although high‐grade vesicoureteral reflux with intrarenal reflux can be treated conservatively, physicians should take into account the higher risk of breakthrough urinary tract infections.