 This is a prospective randomized open-label pilot study to investigate the effect of mycophenolate mofetil treatment in patients with abnormal urine protein excretion due to membranous nephropathy MN or focal segmental glomerulosclerosis FSGS. The change in urine protein excretion will be the primary outcome studied. The treatment regimen comprising prednisolone and mycophenolate mofetil will be compared with prednisolone and chlorambucil in MN, and compared with prednisolone in FSGS. The study duration will be 12 months for each patient. 