Bacillus Calmette-Guérin (BCG) and interferon-alpha2B (IFN-alpha2B) have both been individually used for the intravesical treatment of superficial bladder cancer. We report our experience on the therapeutic efficacy and toxicity of combined intravesical BCG plus IFN-alpha2B for treating superficial bladder cancer, including patients failing previous BCG therapy. Thirty-two patients with superficial bladder cancer underwent 6 weekly treatments with full-, one-third, or one-tenth-dose of BCG plus 50 or 100 MU of IFN-alpha2B based on prior BCG exposure and tolerance. Patients with no evidence of disease proceeded onto maintenance therapy of 3 weekly treatments at 3 months followed by 2 additional maintenance cycles given 6 months apart. Response was assessed by cystoscopy/biopsy every 3 months after treatment. Before BCG plus IFN-alpha2B treatment, 20 patients (63%) had previously failed intravesical BCG therapy, 27 (84%) had aggressive disease (stage T1, grade 3, or carcinoma in situ), 27 (84%) had recurrent disease, 14 (44%) had multifocal disease, and 6 (19%) had disease of over 4 years duration. At median follow-up of 22 months, 21 patients (66%) remain disease-free and 11 patients (34%) had disease-recurrence. Nineteen of 32 patients (59%) were disease-free after the initial induction cycle. Six of 11 patients 55% ultimately failing combination therapy did so at the first 3 to 4 month evaluation. Four of 7 patients (57%) benefited from salvage re-induction therapy. Of the 20 patients previously treated with BCG, 12 patients (60%) remain disease-free. Combination BCG plus IFN-alpha2B intravesical therapy was well tolerated. Combination intravesical BCG plus IFN-alpha2B is an effective and tolerable alternative for patients with superficial bladder cancer, including those patients in whom intravesical BCG therapy had previously failed. Benefits of this combination therapy may include potentially less morbidity, improved clinical efficacy, and in the long term, fewer patients undergoing radical therapy. However, radical treatment options should be pursued for early failures of this combination regimen in those patients with risk factors for recurrence and progression.