PURPOSE: IgA nephropathy (IgAN) is one of the major causes of end-stage renal disease. Mass school urine screening (SUS) has been performed to enable early detection of chronic renal diseases, including IgAN. We wanted to evaluate the patients with IgAN, including those diagnosed through SUS. METHODS: Between 1998 and 2010, 64 children were diagnosed with IgAN based on renal biopsy results obtained at the Pediatric Nephrology Department, OO University Hospital. We divided these patients into the SUS group (37 cases), diagnosed through SUS, and the symptomatic (Sx) group (27 cases), diagnosed clinically. The medical records of both groups were analyzed retrospectively. RESULTS: The mean age of the SUS and Sx groups was 10.8+/-2.7 and 9.5+/-3.4 years (P>0.05), respectively. Both groups had a higher proportion of male patients. The time from the notification of an abnormal urinary finding to a hospital visit or renal biopsy was shorter in the Sx group than in the SUS group. Regarding clinical manifestations, there were fewer cases with gross hematuria (P<0.001) and edema (P=0.008) in the SUS group, but there were no differences in terms of the therapeutic regimen and treatment duration. Regarding laboratory parameters, the Sx group had a higher white blood cell count (P=0.007) and lower hemoglobin (P=0.007) and albumin (P=0.000) levels. There were no differences in the renal biopsy findings in both groups, based on the history of gross hematuria or the severity of proteinuria. However, in all 64 patients with IgAN, the light microscopy findings (Hass classification) were related to a history of gross hematuria or the severity of proteinuria. CONCLUSION: There were no significant clinical and histological differences between the groups, as both had early stage IgAN. Although SUS facilitates the early detection of IgAN, long-term, large-scale prospective controlled studies are needed to assess the benefits of early diagnosis and treatment in chronic renal disease progression.