Extracellular curved striated bodies and round bodies were found in 62 and 41 per cent, respectively of 360 renal biopsies performed in children with a variety of nephropathies. They were observed in the basal lamina and mesangial matrix. The fact that they commonly occurred together appears to suggest a common aetiology and they are probably derived from altered protein of the basal lamina and mesangial matrix, or from proteins of immune deposits.