Chronic kidney disease is a major public health issue that is estimated to affect 10% of New Zealanders. Chronic kidney disease increases the risk of kidney failure, premature heart disease and death. Kidney failure causes a significant social and financial burden to patients and their families and generates a significant cost to the New Zealand public health system. Current therapies to slow or prevent chronic kidney disease are only partly effective with many patients developing kidney failure despite optimal therapy. Experimental animal studies and small clinical studies suggest that lowering uric acid may be helpful to slow or prevent the progression of kidney disease. This is a multi-centre, multi-national double-blind, randomised trial which will enrol 100 New Zealand patients who will receive allopurinol or a placebo. It will determine whether therapy to lower uric acid can slow the progression of chronic kidney disease, reduce cardiovascular events and reduce mortality.