This double blinded randomised controlled prospective study evaluated the effects of feeding a renal diet with modified phosphorus, sodium, and lipid content for cats with stage 2 or 3 chronic kidney disease versus feeding an adult maintenance diet. Results revealed that serum urea nitrogen concentrations were significantly lower and blood bicarbonate concentrations were significantly higher in the renal diet group at baseline and at 12 and 24 months. A significantly greater percentage of cats fed the maintenance diet had uraemic episodes (26%), compared with cats fed the renal diet (0%) and a significant reduction in renal-related deaths but not all causes of death was detected in cats fed the renal diet.