The origin of pelvic serous carcinoma continues to be controversial. Recent studies of patients undergoing primary surgery for ovarian, primary peritoneal, and uterine serous carcinomas have indicated the value of complete fimbrial sampling for detecting occult serous tubal intraepithelial carcinoma (STIC). Evidence suggests that a significant proportion of pelvic serous carcinomas may arise from in situ lesions on the distal fallopian tube. In this study, 14 consecutive cases of interval debulking surgery after neoadjuvant chemotherapy were reviewed, using both hematoxylin and eosin staining and, as needed, immunohistochemistry for p53 and MIB-1. The degree of fimbrial sampling was evaluated, and cases were examined for tumor involvement in the endosalpinx and the presence of STIC. Tumor treatment response was classified using a semiquantitative 4-tier scale. The results indicate that STIC can persist despite chemotherapy and can be readily identified during microscopic examination. These results are expected to improve the quality of the pathology evaluation by providing data-driven recommendations for sampling in interval surgery cases and showing the value of a systematic approach to evaluating the fallopian tube (sectioning and extensively examining the fimbria protocol). These results demonstrate that a tubal primary can still be assigned in these situations. Finally, this study raises interesting biologic questions about the sensitivity of cells originating from serous cancer tumor to chemotherapy. The presence or absence of STIC in specimens from interval surgery after neoadjuvant treatment has not previously, to our knowledge, been addressed.