Background: Prostatic cyst is a rare disease of prostate, with 0.5–7.9% prevalence. It is often asymptomatic and found accidentally using abdominal ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). It is a rare pathology which can be confused with diseases of prostate like benign hyperplasia of prostate or carcinoma prostate which are much more common in old age. Case description: A 70-year-old male presented to emergency department with complaints of acute urinary retention and constipation. Abdomen was opened via a lower midline incision revealing a large cystic lesion of prostate which was aspirated (550 mL approximately, brownish in color) and deroofing of cyst wall was done. Complete excision could not be done due to the presence of adhesion with rectal wall. Histopathology report confirmed it to be a benign cyst of prostate. Discussion: Existing literature of prostatic cysts are highlighting its infrequent occurrence. The etiological factors of prostatic cyst include inflammatory disease, benign prostatic hyperplasia, ejaculatory duct obstruction, atrophy of prostate gland, and tumor. In our case, the patient had urinary retention and constipation which was related to large size of the cyst. The differential diagnosis includes bladder diverticulum, teratoma, seminal vesicle cyst, epididymal cyst, and Wolffian duct cyst.