Tc-tilmanocept received recent Food and Drug Administration approval for lymphatic mapping in 2013. However, to our knowledge, no prior studies have evaluated the use of Tc-tilmanocept as a single agent in sentinel lymph node (SLN) biopsy in breast cancer. We executed this retrospective pilot study to assess the ability of Tc-tilmanocept to identify sentinel nodes as a single agent in clinically node-negative breast cancer patients. Patients received a single intradermal injection overlying the tumor of either 18.5 MBq (0.5 mCi) of Tc-tilmanocept on the day of surgery or 74.0 MBq (2.0 mCi) on the day before surgery by a radiologist. Immediate 3-view lymphoscintigraphy was performed. Intraoperatively, SLNs were identified with a portable γ-probe. A node was classified as hot if the count (per second) of the node was more than 3 times the background count. Descriptive statistics are reported. Nineteen patients underwent SLN biopsy with single-agent Tc-tilmanocept. Immediate lymphoscintigraphy identified at least 1 sentinel node in 13 of 17 patients (76.5%). Intraoperatively, at least 1 (mean, 1.7 ± 0.8; range, 1-3) hot node was identified in all patients. Three patients (15.8%) had 1 disease-positive SLN. In this small, retrospective pilot study, Tc-tilmanocept performed well as a single agent for intraoperative sentinel node identification in breast cancer. A larger, randomized clinical trial is warranted to compare Tc-tilmanocept as a single agent with other radiopharmaceuticals for sentinel node identification in breast cancer.