A 14-year-old female neutered domestic shorthair cat was evaluated for a palpable abdominal mass, polyuria and polydipsia. Physical examination revealed a tense and distended abdomen. Blood work revealed moderate azotaemia. Both kidneys were reduced in size with decreased corticomedullary distinction and hyperechoic parenchyma. The kidneys were surrounded by a large subcapsular accumulation of anechoic fluid. Diagnosis of bilateral perinephric pseudocysts (PNP) and chronic renal disease was made. The PNP recurred three days post drainage. Fluid was consistent with a modified transudate. Medical treatment with diet and angiotensin converting enzyme inhibitor was started. PNP are uncommon subcapsular accumulation of fluid around the kidneys. Main differentials include urinoma and neoplasia, and therefore, the clinical history and examination of the fluid are important features in the work-up of these patients.