Activated protein-1 (AP-1) plays a pivotal role in the progression and prognosis of proteinuric renal disease and it is an important mediator of the tubulointerstitial inflammatory process, which is a final common pathway for progressive renal injury in most renal diseases. Our study included 30 patients divided into 20 patients with primary nephrotic syndrome, 10 of them with FSGS and 10 with other renal pathology. The remaining 10 patients had ARF. The aim of our study is to investigate the role of AP-1 in the progression of renal disease and its value in the prognosis of patients with nephrotic syndrome and acute renal failure through estimation of its level of expression in renal tissue during active disease process.