Intraoperative assessment of colon cancer resection specimens may influence immediate surgical management. Indications for evaluation include determining the depth of invasion, presence of serosal penetration, status of margins, and intactness of the mesorectum, when present. Pathologists may also be asked to identify residual carcinoma in neoadjuvantly treated patients, or document the presence of other lesions, such as adenomas, polypectomy sites, or underlying colitis. Estimating the depth of invasion into the colonic wall is best achieved by macroscopic examination in combination with frozen section analysis, whereas detecting serosal involvement may require touch or scrape preparations of the serosal surface. Assessment of margins is most challenging in rectal specimens, particularly when patients have received neoadjuvant therapy.