Purpose: To report our experience with symptomatic extravasation of intravesical chemotherapy administered within 24 h after transurethral resection (TUR) over the past 10 years. Methods: We identified all consecutive patients who presented with symptomatic extravasation of intravesical chemotherapy following TUR between 2001 and 2011. We assessed the severity of the postoperative complications using the modified Clavien system. Results: We identified 9 patients (mean age 59, range 40–76 years) with symptomatic extravasation. One patient had grade II, 2 had grade IIIa, and 5 patients had grade IIIb complications according to the Clavien system. Surgery was needed in 6 of 9 patients. One required ICU management (Clavien IV). No patients died in the postoperative course. Conclusion: Extravasation can cause severe complications and diagnosis is often protracted. Considering the growing practice of immediate intravesical instillations, the number of patients with symptomatic extravasation is expected to rise. An increased awareness of this possible complication is warranted.