Ovarian tumors are of the dermoid type in 10% of the cases, and are bilateral in 12% of the cases. The most frequent complications are Torsion in 12% of the cases; infection in 2% of the cases; rupture in 1.3% of the cases. Malignant change is low (1%). These complications are more frequent during pregnancy. Rupture of a dermoid cyst can be either the consequence of torsion or infection, or can be spontaneous. The rupture can occur within a hollow viscus (bladder, rectum, vagina) or within the peritoneal cavity. Reports of intraperitoneal ruptures are more frequent in recent literature. So far 16 cases of spontaneous rupture have been reported, and this paper is adding 2 new cases. The 1st case concerns a patient who has been treated for pelvic inflammatory disease for many years; she suddenly developed an acute abdominal syndrome, which was diagnosed as rupture of tubo-ovarian abscess, but on exploratory laparotomy, the peritoneal cavity was filled with yellow sebaceous material, admixed with hair. A non-twisted ruptured dermoid cyst was found, the rest of the pelvic organ being absolutely normal. Post-operatively she developed a severe paralytic ileus, which responded to conservative management. The 2d case is a patient who was explored for an asymptomatic pelvic mass, which was a dermoid cyst. On one area over the dermoid cyst, there was a dark hemorrhagic loculation and the adjacent portion of the peritoneum was infiltrated with a firm nodular implant; the microscopic findings were highly suggestive of a tiny silent rupture. The main conclusion is that the symptomatology is determined by the amount of the contents of the cyst expelled in the peritoneal cavity. The cases presented here are the 2 extremes.