Purpose <p>To investigate the safety and effectiveness of transcatheter arterial embolization (TAE) with tris-acryl gelatin microspheres in patients with symptomatic enlarged polycystic kidneys (PCKs).</p> Material and methods <p>This prospective study was planned as a safety trial for patients with symptomatic enlarged PCKs who complained of a marked abdominal distention, gastroesophageal reflux, or abdominal pain. We then assessed renal volume reduction and improvement in clinical symptoms as secondary endpoints. The patients after induction of dialysis therapy (urinary volume less than 500&#xa0;mL per day) were included. Bilateral renal TAE with tris-acryl gelatin microspheres injection followed by metallic coils placement was performed, and adverse events, clinical symptoms, abdominal circumference, blood pressure, dry weight and laboratory data were evaluated at 1, 3, 6 and 12&#xa0;months after TAE. Each kidney volume was calculated before TAE and at 3, 6 and 12&#xa0;months after TAE.</p> Results <p>Six kidneys of three patients (65-, 58- and 54&#xa0;years women) were treated. All three patients experienced abdominal pain, vomiting and inflammatory reactions immediately after TAE; however, abdominal pain and vomiting resolved within their hospitalization period, and inflammatory reactions improved during the follow-up period in all patients. Accelerated renal anemia was ameliorated by temporary blood transfusions and increased doses of erythropoiesis-stimulating agent or darbepoetin alpha during dialysis. The mean kidney volume was 3885&#xa0;mL before TAE and 3025, 2320 and 1832&#xa0;mL at 3, 6 and 12&#xa0;months after TAE, respectively.</p> Conclusion <p>Renal TAE with tris-acryl gelatin microspheres is considered a safe and effective treatment for symptomatic enlarged PCKs.</p> Trial registration <p>This clinical trial was registered with the University Hospital Medical Information Network (UMIN) under the registration number UMIN000016576.</p>