A 16-year-old female was admitted to our hospital because of chance proteinuria. On admission, mild proteinuria (0.6g/day) was observed, but microhematuria was not detected during the observation period. All the values of the renal function tests were within the normal range. Her renal biopsy demonstrated a prominent increase in the mesangial area by light microscopy and showed marked paramesangial hemispherical deposits by electron microscopy. Though IgM, IgG, Clq, C3, and fibrinogen were localized in the mesangial region, IgA was not detected by immunofluorescence study. It has been reported that paramesangial hemispherical deposits are strongly indicative of IgA glomerulonephritis. We conclude that this patient is a rare case of non-IgA glomerulonephritis with huge paramesangial hemispher ical deposits.