IgA nephropathy (IgAN) is a relatively common glomerulopathy in children and adolescents. The etiology of this disease is uncertain. We previously reported a child with IgAN who developed acute interstitial nephritis. We now describe three pediatric patients, including the index case, who had IgAN and who developed concomitant acute interstitial nephritis in association with renal functional impairment. We suggest that this histopathological lesion be considered in any child with IgAN and unexpectedly severe kidney dysfunction.