Lipoid nephrosis or idiopathic nephrotic syndrome, the most frequent glomerular disease in childhood, is defined by the association of a nephrotic syndrome and minimal changes on renal biopsy or unspecific lesions such as focal and segmental glomerular sclerosis or diffuse mesangial proliferation. Several complications related to the nephrotic syndrome may occur: infections particularly bacterial infections, thrombo-embolic accidents, hypovolemia with shock. Other complications are secondary to the treatment: steroid therapy, immunosuppressants. The outcome is related to the response to steroid therapy. In case of steroid responsiveness, the risk is the relapse when the steroid dosage is tapered or stopped and the complications related to the treatment which is given to maintain remission. In case of steroid resistance, the risk is that of progression to renal failure which occurs in approximately 50% of patients after 5 years. Moreover, the nephrotic syndrome may recur after renal transplantation.