Periurethral injection of bulking agents to cause coaptation of the urethral walls has long been used in the treatment of urinary incontinence. A new form of this treatment is the silicone Genitourinary Spheroidal Membrane (Genisphere), which is placed in the periurethral tissues with a special delivery tool. Among 39 women who received two or three Genispheres, 29 (77%) became dry or markedly improved with a significant increase in leak-point and proximal urethral closure pressures. Early sexual activity, a short urethra, atrophic tissue, bladder instability, incorrect positioning, and device rupture were the causes of failure. The device has several advantages over traditional bulking agents, including the absence of silicone particles that can migrate, and has proved to be a safe method of treating stress urinary incontinence.