A bronchogenic cyst is regarded as a developmental abnormality of the primitive foregut, which typically occurs in the mediastinum. The cystis normally diagnosed in relation to respiratory problems or recurrent infections in children. In adulthood, it is a rare pathology, and its diagnosis is usually incidental. Moreover, subdiaphragmatic and retroperitoneal locations are exceptionally rare. A 60-year old woman presented with an incidental left retroperitoneal mass that was suspected of being a non-functioning retroperitoneal tumor. After evaluating the general radiologic and endocrinologic work up for a retroperitoneal tumor, a laparoscopically complete resection was performed with primary repair of the attached diaphragm. The surgically resected cyst measured 7x5x5 cm and was filled with mucin material. Histologically, the cyst wall was lined by a ciliated pseudostratified or tall columnar epithelium without dysplastic changes. The diagnosis of a bronchogenic cyst in the retroperitoneum was confirmed. We present this case with a review of the relevant literature.