Primary peritoneal carcinoma is defined as an adenocarcinoma arising in the peritoneum, with or without minimum ovarian involvement. It was described for the first time by Martin A. Swerdlow in 1959 and since then it has been issue of investigation, but the knowledge we had about it is scant; however, the similarities with ovarian surface epithelial carcinoma are fascinating. Primary peritoneal carcinoma is a rare tumor with a frequency of about 10% with respect to ovarian carcinoma. The predominant histological subtype by far is serous adenocarcinoma. However, other subtypes have been reported and it is found almost exclusively in women but there are a few reports of cases in men. The known risk factors to date are age, feminine sex, and mutation of the breast cancer early onset 1 (BRCA1) gene. The clinical presentation of primary peritoneal carcinoma is heterogeneous, and its diagnosis is based on the presence of a serous carcinoma with predominant peritoneal tumor load, with scant or no ovarian involvement. Generally it presents with disseminated peritoneal carcinomatosis with abdominal discomfort and ascites as the main symptoms. The lymph node dissemination has been a wide source of study; there is no characteristic spread pattern, but it has been observed that up to 63.9% of patients have retroperitoneal lymph node metastasis. It is always important to consider and search for a primary peritoneal carcinoma diagnosis in all patients with peritoneal carcinomatosis, because their clinical heterogeneity could distract the attention of the diagnosis and lead to a misdiagnosis with the consequent increase in mobility and mortality for a wrong treatment.