Many patients have chronic, debilitating symptoms of voiding dysfunction that are refractory to conventional medical or surgical therapies. This multicenter, prospective study evaluated the long-term effectiveness of sacral nerve stimulation using the implantable Medtronic InterStim therapy for urinary control in patients with otherwise intractable complaints of urinary urge incontinence, urgency-frequency, or retention. Each patient first underwent temporary, percutaneous sacral nerve test stimulation. If at least a 50% reduction in target symptoms was documented for at least 3 days, patients received a permanent Medtronic InterStim sacral nerve stimulation system that includes a surgically implanted lead and neurostimulator. Regular follow-up was conducted with outcome data. We report here on patients who have been observed from 1.5 to 3 years postimplantation. The results demonstrate that after 3 years, 59% of 41 urinary urge incontinent patients showed greater than 50% reduction in leaking episodes per day with 46% of patients being completely dry. After 2 years, 56% of the urgency-frequency patients showed greater than 50% reduction in voids per day. After 1. 5 years, 70% of 42 retention patients showed greater than 50% reduction in catheter volume per catheterization. We conclude that the Medtronic InterStim therapy for urinary control system is an effective therapy with sustained clinical benefit for patients with intractable symptoms of urinary urge incontinence, urgency-frequency, or retention.