This study investigated the possible relationships between renal resistive index (RI) or pulsatility index (PI) and systolic blood pressure and biochemical and haematological parameters in dogs and cats with renal disease. The study included 50 dogs and 20 cats with renal disease. RI and PI were significantly higher in both dogs and cats with renal disease than in 27 healthy dogs and 10 healthy cats. In dogs, a significant negative correlation was found between RI and red blood cell count, and a positive correlation was found between PI and serum creatinine. In cats, a positive correlation was found between RI and serum urea, between PI and serum creatinine, and between PI and serum urea. No relationship could be found between either RI or PI and systolic blood pressure.