Chronic allograft nephropathy continues to be a major cause of kidney transplant loss and return to dialysis. Treatment options are limited and the course of the disease tends to be progressive. This trial is designed to prevent a major mediator of this process, namely the expansion of the cortical interstitial compartment of the kidney where most of the scarring occurs. The drug being studied, Losartan, has proven efficacious in a number of kidney diseases.

Ages Eligible for Study:  18 Years and above,  Genders Eligible for Study:  Both

Criteria

Inclusion Criteria:

• Age > 18 years.
• Recipients of a first or a second renal transplant alone or in combination with a pancreas transplantation.
• Informed consent
• Adequate baseline biopsy; at least 10 cortical projection fields.

Exclusion Criteria:

• Age < 18 years.
• Serum creatinine 2.5mg/dL.
• Persistent hyperkalemia; potassium > 5.4 mEq/L.
• Known hypersensitivity to losartan or iodine allergy.
• Documented renal artery stenosis by duplex ultrasonography.
• Recipients of grafts from an HLA-identical sibling.
• Recipients whose primary renal disease is primary hyperoxaluria,dense-deposit disease, focal segmental glomerulosclerosis or hemolytic uremic syndrome.
• Women of childbearing age who wish to become pregnant and/or are unwilling to use contraceptive measures or who are pregnant.
• Recipients requiring ACE inhibitors or AII blockers for a cardiovascular indication (e.g. systolic dysfunction).
• Recipients who are > 55 years old and had a history of cardiovascular disease (coronary artery disease, stroke or peripheral vascular disease).