The aim of this study was to evaluate the long-term effectiveness and safety of the tension-free vaginal tape (TVT) procedure. In a Nordic three-center prospective observational cohort study, 90 women with primary stress incontinence had a TVT operation performed in local anesthesia. Assessment included a 24-h pad test, a stress test, physical examination, and a visual analog scale for assessing the degree of bother. Patient's global impression of cure was obtained, and condition specific quality of life questionnaires were used. Seventy-seven percent of the initial cohort of 90 women and 89% of those alive and capable of cooperating were assessed 11.5 years after the TVT operation. Ninety percent of the women had both a negative stress test and a negative pad test being objectively cured. Subjective cure by patients global impression was found in 77%, 20% being improved and only 3% regarded the operation as a failure. No late-onset adverse effects of the operation were found, and no case of tape erosion was seen. The TVT procedure is safe and effective for more than 10 years.