Breast lymphoscintigraphy using (99m)Tc-sulfur colloid ((99m)Tc-SC) is well established in clinical practice for staging patients with breast carcinoma. Nearly all patients report having pain during the procedure. However, techniques used to minimize pain during breast lymphoscintigraphy are highly variable across institutions. Our study was to determine whether anesthetizing the skin with sodium bicarbonatehether-buffered lidocaine before performing breast lymphoscintigraphy reduced the pain experienced by the patients. The second objective of this study was to evaluate whether anesthetizing the skin with buffered lidocaine changed visualization of lymph nodes. METHODS This prospective, patient-masked and randomized study involved performing breast lymphoscintigraphy in a control group and experimental group of female breast cancer patients. The control group did not receive skin anesthetic before (99m)Tc-SC injections, whereas the experimental group first underwent skin anesthesia with an injection of 2% sodium bicarbonate-buffered lidocaine. All patients were asked to rate their pain levels, using the National Institutes of Health pain scale, before the procedure and immediately after the injections. The change in pain from baseline was compared between the 2 groups. After the injections, scintigraphic imaging of the axilla was performed, and the number of axillary lymph nodes visualized was recorded. RESULTS No significant difference was found in preprocedural baseline pain from the control group, compared with the experimental group. There was a statistically significant difference in the increase in pain experienced during the procedure between the control group and the experimental group (P = 0.009). There was no significant difference in the detection of lymph nodes between the control and experimental groups (P = 0.56). CONCLUSIONS The results from our study indicate that injecting subcutaneous buffered lidocaine before intradermal injection of (99m)Tc-SC for breast lymphoscintigraphy significantly decreases patient pain without interfering with lymph node visualization.