Objective: Serous tubal in situ carcinoma (STIC) has been defined as one important precursor of pelvic serous cancer. Morphologically, STIC is defined by are cytologic atypia, high proliferative index and strong staining for p53. Method: The present study evaluates the presence of STIC and p53-signature in consecutive cases of 12 prophylactic salpingo-oophorectomy in women with BRCA-1-mutaion (BSO), 11 macroscopically inconspicuous tubes of patients with primary tubal cancer (TC) and 9 cases of primary peritoneal cancer (PPC) using immunohistochemistry against Ki-67 and p53 (clone DO-7). Results: The frequency of p53-signature and STIC was 8 % and 0 % in cases of prophylactic surgery, 9 % and 18 % in TC and 0 % and 33 % in PPC.