Case series summary Six cats were diagnosed with renal abscesses. Common clinical findings were lethargy, dehydration, abdominal pain and nephromegaly. Fever was noted in half of the cases. Diagnosis was established by ultrasonography, cytological examination and bacterial culture of abscess aspirates. At least one possible contributing factor could be identified in all cases. Antibiotics were consistently used and in two cats the abscess was surgically drained. The short-term outcome was fair but the long-term outcome was dependent on the underlying condition. Relevance and novel information The results of this small case series suggest that renal abscess should be considered when nephromegaly and/or abdominal discomfort are noted. Diagnosis of renal abscess is straightforward when ultrasonography and fine-needle aspirate analysis can be performed. Medical treatment is assumed to be preferable but surgical treatment may be warranted on a case-by-case basis. Given that almost every affected cat was diagnosed with at least one comorbidity, a thorough evaluation is recommended for all cats with renal abscesses.