A total of 178 patients with grade 1 noninvasive (stage Ta) bladder tumors followed from 1 to 10 years (median 58 months) was prospectively evaluated by cystoscopy, transurethral resection, mucosal biopsies, cytology, size and number of tumors at diagnosis, recurrences, progression in grade and stage, number of negative or positive cystoscopies and death from all causes. Histopathological and cytological studies were confirmed by a Central Pathology Laboratory using the criteria for grade 1 as described previously. Of the patients 122 (68.5%) had a single tumor. Three-quarters of the patients had tumors of less than 2 cm., 95% had mild or no urothelial dysplasia and 1 had positive cytology results. There were 419 recurrent tumors in 109 patients (61%). Patients with multiple tumors were at a significantly greater risk for recurrences (p < 0.001). Size of tumor significantly affected the rate of recurrence in the first 2 years after initial diagnosis in single tumor patients only. Of the multiple tumor patients 90% experienced a recurrence compared to 46% of the single tumor patients. Of the 1,112 cystoscopies performed in 122 single tumor patients 18% were positive, compared to 33% of the 686 cystoscopies performed in 56 multiple tumor patients. A total of 29 patients had a change in grade, 5 having grade 3 and 24 having grade 2 tumors. Progression to stage T1 occurred in 5 patients and to stage T2 or greater in 3. Of the 36 patients who died, 1 died of obstruction due to bladder cancer. Experimental evidence supports the opinion that the cells of stage Ta, grade 1 tumors are different in several ways from normal urothelium. There are little data to support the use of the term papilloma to describe stage Ta, grade 1 tumors without reservation. The data demonstrate that the tumor diathesis being expressed ceases with time and for unknown reasons. Multiple tumor patients with stage Ta, grade 1 disease might be included in chemotherapy trials only with stratification and a control arm of transurethral resection/fulguration alone.