Radiologic investigation is a crucial source of clinical information in many disorders of the urinary bladder. However, in cases such as urologic infection, trauma, and neuro-urology, radiologic investigation is often limited, and the diagnosis must be approached by combining clinical history, cystoscopy, histopathology, and laboratory findings. In particular, cystoscopy is essential for diagnosing some types of cystitis, and in neuro-urology, urodynamic study must be considered for diagnosis. Additionally, some benign inflammatory diseases cannot be differentiated from bladder tumors; thus, cystoscopy biopsy is essential for diagnosis. Therefore, radiologists should understand the various diagnostic tools used in bladder and should strive to produce a radiologic report that takes into account the characteristics of the disease.