A pharmacokinetic and pharmacodynamic study of Basiliximab therapy has not been reported in recurrent post-renal transplant nephrotic syndrome. We assessed the effect of urinary protein in a focal segmental glomerulosclerosis patient. We measured the serum concentrations of basiliximab as well as the rate of activated CD25-positive T lymphocytes at fixed intervals in nephrotic versus eight nonnephrotic pediatric post-renal transplant patients. A significant reduction in the antibody concentrations was observed in focal segmental glomerulosclerosis. The CD25 expression rate showed a similar trend to the pharmacokinetic data. We conclude that cases of massive urinary protein excretion need special care to maintain immunosuppression in renal transplant using Basiliximab.