Vernix caseosa peritonitis is a rare complication caused by inflammatory response to amniotic fluid spilled into the maternal peritoneal cavity. Most cases occur after cesarean section. We discuss herein two patients, aged 33 and 29 years, who presented with vernix caseosa peritonitis seven to nine days after a cesarean delivery. Laparotomy was performed and it revealed neither uterine rupture nor other surgical emergencies, but cheesy exudates on the serosal surface of all viscera. Appendicectomy was performed. Histopathologic study revealed acute fibrinous serositis and a mixed cellular infiltrate, rich in neutrophils, around fetal desquamated anucleate squamous cells. Patients´ recovery was complete. Clinical diagnosis of vernix caseosa peritonitis should be suspected in patients presenting post-cesarean section with an acute abdomen. Distinctive histopathologic findings allow making the correct diagnosis. Vigilant monitoring after diagnosis is essential as delayed morbidities may appear.