Endometriosis of the bladder is an uncommon lesion and is seen in 1% of all cases of endometriosis. Fewer than 200 cases have been reported in the worldwide literature. It exists in two forms, primary and secondary. The primary form is generally a part of generalized pelvic disease, whereas the secondary is iatrogenic, that is, it occurs after pelvic surgery like caesarean section or hysterectomy. We report an additional case of an isolated bladder detrusor endometriosis which developed after an cesarean section and which was diagnosed 4 years after symptoms. Medical treatment was unsuccessful. Cystotomy and excision of endometriosis was performed. Diagnostic and therapeutic options are also discussed briefly.