Introduction: Female stress urinary incontinence (SUI) is often treated surgically. Urethral bulking agents are a minimally invasive alternative, especially in patients suffering from intrinsic sphincter deficiency, but often with limited long-term efficacy. Urolastic® is a non-deformable, non-resorbable silicone elastomer that is used as an injectable. Its properties might result in a more durable response after injection. If this durability factor can be combined with a low complication rate, this can become a useful treatment option. We therefore assessed the subjective improvement and safety after treatment with Urolastic®. Materials and Methods: In 2 Dutch hospitals, 65 patients were treated with Urolastic®. The subjective improvement was assessed and the medical charts were reviewed for complications that appeared during the follow-up period. The complications were classified using the Clavien-Dindo classification. Results: We found that 76-88% of the patients showed subjective improvement at 12-25 months follow-up. The rate of improvement experienced was 50-70%. The rate of complications classified as Clavien-Dindo >II was 24-33%. The 12 patients with 75-100% subjective improvement after 2 months, showed 85% improvement after a median of 25 months. Conclusions: With careful patient selection, Urolastic® seems to be a safe, durable and effective treatment option for female SUI.