Summary—Thirty‐eight cases of large bladder diverticula treated surgically between 1970 and 1979 were reviewed. Twenty‐two underwent diverticulectomy alone and 19 of these had no further trouble during a follow‐up period averaging 4.5 years. Three other patients who had undergone resection of a small prostate gland prior to diverticulectomy might also have been cured by diverticulectomy alone. In at least half of the patients presenting with large bladder diverticula no obstructive factor was present and it is concluded that primary diverticula are more common than was previously thought.Clinically, primary diverticula may be distinguished from secondary on the basis of symptoms, cystoscopic findings of trabeculation and urodynamic studies. A more extensive application of the transperitoneal approach in performing diverticulectomy is reco