We report a case of bilateral hydronephrosis caused by pseudolymphoma of bilateral renal pelves. A 52-year-old woman with Sjogren's syndrome and bronchial asthma was found to have bilateral hydronephrosis. Abdominal plain computerized tomography showed an irregular thickening of the bilateral renal pelves with moderate hydronephrosis. The gallium scintigraphy revealed intense tracer uptake in bilateral renal pelves. Open biopsy of the right renal pelvis was performed under the diagnosis of malignant lymphoma. The pathologic diagnosis was pseudolymphoma of the renal pelvis. Steroid therapy dramatically improved pseudolymphoma and hydronephrosis within a month. There were no signs of recurrence.