T1 transitional cell cancer of the urinary bladder is associated with a significant risk of tumor progression when transurethral resection (TUR) is the only treatment. Additional intravesical immunotherapy can reduce this risk; however, long-term results of more than 15 years of follow-up indicate that almost half of the patients may lose their bladder or even die due to recurrent tumor. The alternative to TUR is cystectomy at either the initial presentation or time of first recurrence. However, although the results of this treatment strategy are encouraging, an unknown percentage of patients will lose their bladder and go on to experience all possible complications of urinary diversion unnecessarily. The central issue of conservative treatment but also the indication for cystectomy is the quality of TUR. From the present literature, it is evident that a 'textbook TUR' cannot be performed on every patient, i.e. macroscopical clearance of the bladder from tumor, separate thorough resection of the tumor base and separate biopsies of the borders of the resection area. Moreover, even in cases of a so-called 'correct TUR', a significant percentage of residual tumor is left behind and will be the source of local recurrence or progression. In addition, TUR specimens may be difficult to diagnose accurately, especially in respect to grade and stage. Recent publications demonstrate that the routinely performed second TUR detects residual tumors of similar or higher stage in a significant percentage of patients. The clinical implications of these findings can be considerable as the absence or presence of tumor may determine whether patients undergo conservative or aggressive treatment. Moreover, results of retrospective studies support this suggestion. Currently, there is no standard appropriate treatment of T1 tumors. However, we strongly recommend that future studies on the conservative treatment of T1 tumors include a second TUR within 2 to 4 weeks after the first one.