Cystitis glandularis (CG) is defined as glandular metaplasia of bladder urothelium. In most cases the course of CG is asymptomatic. However, some patients complain of hematuria and lower urinary tract symptoms (LUTS) of varying degrees. We present a case of 45-year-old man with an extensive CG causing acute urinary retention. Although it was initially treated as an infection, prompt ultrasound and cystoscopy helped to establish the diagnosis. Transurethral resection of the cyst with biopsy of the bladder mucosa was then performed. Immediately after surgery the patient noticed significant improvement in urine passing. During the 2-month follow-up there was no relapse.