Background: Nephrotic syndromes and acute renal failure are very common diseases. NF-кB is a protein complex that controls the transcription of DNA. Recent data have shown that NF-кB is activated in tubules and glomeruli in various experimental models of renal injury. During the last few years, a number of articles have suggested that the detection of NF-кB in various tissues including the kidney may be a sign of injury. Objectives: We addressed the idea that NF-кB could be an indicator of renal damage progression in human proteinuric nephropathies. Methods: We studied the in situ expression of activated transcription factors NF- B in renal biopsy sections of patients with nephrotic syndrome and acute renal failure. Kidney samples were obtained by percutaneous renal biopsy. The renal biopsies from 20 patients with nephrotic range proteinuria (10 with FSGS and 10 with any other glomerulonephritis) were studied and compared with those from 10 patients with acute renal failure. The diagnosis of GN and acute renal failure was made based on clinical and histological findings. Standard studies were done to exclude secondary causes. Results: The mean NF-кB level was higher in the ARF group (mean 1085, ±SD 463.4) compared to the nephrotic group (mean: 568.8, ±SD 283.4), and FSGS group, (mean 628.4 ±SD 183.1). NF-кB levels resulted in, that patients with MPGN had the highest levels, mean 795 SD ±643.5, followed by the MesPGN patients, mean 598.7, SD ± 166.5. The lowest levels were found in patients with membranous nephropathy, mean 387.5 and SD ± 101.1. There was a positive correlation with the serum creatinine level for all groups of patients before treatment (r=0.531, p=<0.01) and after three months follow up (r=0.568, p=<0.05). Yet we couldn’t elicit a significant correlation with proteinuria except in the FSGS group. Conclusion: we couldn’t prove NF-кB as a predictor for outcome yet further studies need to study the NF-кB subunits in different causes of nephrotic syndrome.