The treatment of high grade T1 bladder cancer remains controversial because of the particularly high risk of recurrence and progression. The purpose of this study was to compare the oncological outcomes of radical cystectomy and a bladder preservation approach using European Organization for Research and Treatment of Cancer (EORTC) risk tables. Among 688 transurethral resections of bladder tumors for patients with non-muscle invasive bladder cancer conducted between 2000 and 2010, 102 patients who had a history of high grade T1 were included. All patients were treated by transurethral resection with additional intravesical Bacillus Calmette-Guerin and 33 patients were treated with deferred radical cystectomy. The risk classifications for tumor recurrence, and progression and survival rates were calculated using the EORTC risk tables. At a follow-up between 48 and 164 months (mean 90.1 months), 53 patients recurred, 34 patients progressed, and 18 patients died. In high grade T1 patients, the probability of progression was 15% in patients in the high risk group and 57% in patients with highest risk at 5 years. The bladder cancer specific survival was 95% in high risk patients and 88% in patients at highest risk at 5 years. High grade T1 bladder cancers are heterogeneous in nature, which complicates treatment decisions. Patients in the highest risk group in EORTC risk tables have different feasible treatment options including early cystectomy.