A patient with a filarial infection due to Loa loa, received single oral dose of ivermectin A few hours after, he has presented a severe renal impairment. Native of the Cameroons, he was also treated for malaria. A renal biopsy has been done, because of chronic proteinuria. It has showed microfilariae in glomeruli, thickening of the basement membrane and a segmental and focal mesangial hyalinosis. By immunofluorescence microscopy there were granular deposits of IgM and C3 along this membrane. Electron microscopy has showed subepithelial electron- dense deposits. This suggests that the renal disease is immunologically induced. During the therapy, adverse reactions seemed to be related with massive liberation of filarial antigens. This is well known with diethylcarbamazine but also now, sometimes with ivermectin.