BACKGROUND: Previous reports have shown that regional lymph node involvement in patients with early-stage breast carcinoma can be evaluated by resection of axillary sentinel lymph nodes (ASLN). Axillary lymphadenectomy may be unnecessary in the absence of ASLN involvement. In the current study, the authors compared the results of ASLN resection in patients with lobular invasive carcinoma (LIC) with the results from patients with ductal invasive carcinoma (DIC) in terms of detection rates and false-negative rates. METHODS: For ASLN detection, technetium 99m sulfur-colloid and patent blue were injected around the tumor. Each patient underwent both ASLN resection and complete axillary lymphadenectomy. Detection rates and false-negative rates were evaluated in patients with LIC and in patients with DIC. RESULTS: Two hundred forty-three patients with invasive, early-stage breast carcinoma were enrolled in the study (208 patients with DIC and 35 patients with LIC). The median patient age, pathologic tumor size, hormone receptor status, and rates of involved lymph nodes were equivalent for both groups. ASLN detection and false-negative rates did not differ for patients with LIC and patients with DIC. CONCLUSIONS: The ASLN detection rate was not dependent on the pathologic type of invasive carcinoma. Pathologic examination of ASLN in patients with LIC and in patients with DIC predicted axillary lymph node status with the same predictive value in terms of lymph node metastasis. For patients with LIC, ASLN examination overestimated the rate of micrometastasis as diagnosed by immunohistochemical techniques. These results will require confirmation in larger studies.