Abstract: Abstract The fine needle aspirates of 41 cases of cytologically positive tumors were immunocytochemically studied. 29 of the 41 cases were verified with subsequent biopsy of post-operative histology. Monoclonal antibodies to CEA, K147+HK₂, K27 and vimentin were used as probes in all cases for immunocytochemical staining with positive and negative control performed. It was found that the metastatic carcinomas were keratin positive, mesenchymal tumors vimentin positive and CEA was an adenocarcinoma marker. K27 expression sensitivity in squamous cell carcinomas was 91.7%, specificity 93.1%, positive predictive value (PPV) 84.6% and negative predictive value (NPV) 96.4%. K147 + HK₂ expression sensitivity in simple epithelial tumors was 81.8%, specificity 94.7%, PPV 94.7% and NPV 81.8%. Vimentin expression sensitivity in mesenchymal tumors was 85.7%, specificity 85.3%, PPV 54.6% and NPV 96.7%. CEA was positive in 72.7% of metastatic adenocarcinoma cases, the specificity being 94.7%, PPV 94.1% and NPV 75%. Keratin expression sensitivity in differentiated and poorly-differentiated carcinomas was not significantly different. In conclusion, the immunocytochemistry of fine needle aspirates was senitive in the diagnosis and classification of tumors, more accurate diagnosis of fine needle aspirates of lymph node tumors can be achieved when McAb immunocytochemistry is incorporated in the cytological studies.