Periurethral injection of bulk-enhancing agents provides a simpler and cost-effective therapeutic approach for stress incontinence in women. We report a case of periurethral granuloma secondary to dextranomer/hyaluronic acid (Dx/HA) copolymer injection. A 73-year-old woman with history of radiotherapy for cervical carcinoma at the age of 55 presented with stress urinary incontinence. She underwent periurethral injection of Dx/HA copolymer, and incontinence was resolved. At 4 months postoperatively, a 3–4 cm noninflammatory painless mass in the external genitalia was noted. Cystic images compatible with urethral diverticula were seen in the magnetic resonance imaging scan, but voiding cystourethrography was unrevealing. Transvaginal tumor puncture yielded abundant creamy material, the culture of which was negative. Microscopic examination revealed refractile foreign material surrounded by foreign body giant cells. Surgical debridement of the granuloma using a cold scalpel was performed. Stress urinary incontinence recurred but resolved spontaneously within 1 month. One year later, the patient continues to be asymptomatic.