To assess the efficacy of fine-needle aspiration biopsy (FNAB) of axillary lymph nodes (ALN), we retrospectively analyzed 140 FNAB of ALN at Memorial Sloan-Kettering Cancer Center, examining technique and cytologic-histologic correlation. Of the 140 FNAB, 124 were performed by the conventional method and 16 by ultrasound guidance (USG). The diagnoses included: unsatisfactory, 20; negative, 38; positive, 72; suspicious, 6; and indeterminate, 4. Positive diagnoses included: carcinoma, 44.4%; melanoma, 43.0%; lymphoma, 5.6%; sarcoma, 5.6%; and mesothelioma, 1.4%; one of which was false-positive, attributed to misinterpretation. All indeterminate and most false-negative cases were due to lymphoproliferative conditions. The sensitivity and specificity of FNAB of ALN were 94.7% and 97.1% and the adequacy rate was 85.7%. The sensitivity, specificity, and adequacy rates of USG FNAB were 100%. Our study shows that FNAB of ALN is an excellent method for diagnosing reactive conditions as well as neoplasms.