Background:  Chronic renal failure or chronic renal disease (CRD) is a progressive oss in renal function over a period of months or years. It is  differentiated  from acute kidney disease  in that the reduction  in kidney function must be present for over 3 months Uremic pruritus is  the most common cutaneous abnormality  in patients  with CRF Uraemic  pruritus  is   unrelated  to  sex,  age,  duration,  cause  of  dialysis,  a  list   of unproven suggestions for  pruritis  include  :     dry skin;  mast  cell proliferation;  Thl cytokines;  secondary hyperparathyroidism;  disturbed balance  between µ-opioid and K• opioid receptors; substance P;  increased skin ions Ca, Mg, PO;  abnormal transmission via the spine .

Nerve  growth  factor  is   a neurotropic  polypeptide  necessary  for the  survival and growth of some central neurons, as well as sensory afferent and sympathetic  neurons.

It has been found that in AD patients increased levels  of NGF in keratinocytes and nfiltrating leukocytes which were related to disease severity . Skin from patients with prurtigo nodularis also have increased  presence of NGF which is  primarily  found in infiltrating leukocytes.

Method:  The present case-control study was carried out on 30 patients with CRF and uraemic pruritus on hemodialysis  who were treated at Sohag Educational Hospital and

20 healthy control  subjects. Patients with CRF and uremic pruritus on hemodialysis  of both sex, any age and not received  any systemic treatment  for pruritus for at least 3 weeks prior to the study were included in this study.

Severity of itching was measured by the 5-D itch score.  5-D is  (duration -  degree -

direction -disability  and distribution).  Maximum  score  is  25 and  indicate severe itching while the minimum score is 5  and indicate no itching. Skin punch biopsies (3 mm) were taken from them for immunohistochemical  studies.

Results: The present study found that in the skin  of the healthy control  participants the expressions of NGF  were seen in the epidermal basal  layer,  but there  was no expression in upper and mid epidermal  cell layers while in dermis about 7 5% of them showed mild expression  and 25% showed moderate expression.

In patients  with chronic CRF with pruritus  on dialysis  the expressions of NGF were strong in epidermal basal layers, upper and mid epidermal  layers. There was a strong expression of NGF in dermis with some spindle like infiltrating cells  especially  in dermal  papillae.