Ganglioneuroma is an uncommon benign tumor of the sympathetic nervous system. In most cases it originates from the thoracic or lumbar portion of the gangliated cord or from the medulla of the suprarenal glands. It is the differentiated form of malignant neuroblastoma. The tumor often manifests itself in young adults by displacement of the surrounding structures. In the case presented the special diagnostic problems of locating the tumor in the pelvis in early pregnancy are discussed.