['To demonstrate the usefulness of a fluorescence imager (photodynamic eye; PDE) for observation of lymph flow in lower rectal cancer (LRC).', 'Between October 2006 and January 2010, PDE observations were performed in 14 patients with LRC. After induction of general anesthesia, a total of 2mL of indocyanine green (ICG) (2.5mg/mL) was injected into the submucosal layer on the dentate line or the anal margin of the LRC.', 'Preoperative PDE observation was able to demonstrate several lymph flows running to the bilateral inguinal areas from the perianal area immediately after ICG injection in 13 of the patients (92.9%). Although these flows were pooled in the bilateral inguinal areas, there was no pooling of such lymph flows in the perianal area. Intraoperative PDE observation was able to demonstrate not only mesenteric lymph nodes in all patients but also bilateral lateral lymph nodes in 13 patients (92.9%). Although 6 patients had undergone sphincter-preserving surgery (SPS), no local recurrence was observed in such patients during the observation period.'] Does fluorescence imaging visualize three sets of regional lymph nodes in patients with lower rectal cancer?