tumor-associated monoclonal antibodies has led to an improved ability to detect occult breast cancer cells in bone marrow aspirates and peripheral blood, further development of this method is necessary before it can be used routinely. One major drawback of immuno-cytochemistry is that only tumor-associated and not tumor-specific monoclonal antibodies are used, and as a result, some cross-reaction with normal cells can occur. In order to effectively stage breast cancer and assess the efficacy of purging regimens prior to autologous stem cell infusion, it is important to detect even small quantities of breast cancer cells. Immuno-histochemical methods are ideal for this purpose because they are simple, sensitive, and quite specific. Franklin et al. performed a sensitive immuno-cytochemical assay by using a combination of four monoclonal antibodies (260F9, 520C9, 317G5 and BrE-3) against tumor cell surface glycoproteins to identify breast tumour cells in bone marrow and peripheral blood. They concluded from the results that immuno-cytochemical staining of bone marrow and peripheral blood is a sensitive and simple way to detect and quantify breast cancer cells. One of the main reasons for metastatic relapse in patients with solid tumours is the early dissemination of malignant cells. The use of monoclonal antibodies (mAbs) specific for cytokeratins can identify disseminated individual epithelial tumor cells in the bone marrow. One study reports on having developed an immuno-cytochemical procedure for simultaneous labeling of cytokeratin component no. 18 (CK18) and prostate specific antigen (PSA). This would help in the further characterization of disseminated individual epithelial tumor cells in patients with prostate cancer. The twelve control aspirates from patients with benign prostatic hypertrophy showed negative staining, which further supports the specificity of CK18 in detecting epithelial tumour cells in bone marrow. In most cases of malignant disease complicated by effusion, neoplastic cells can be easily recognized. However, in some cases, malignant cells are not so easily seen or their presence is too doubtful to call it a positive report. The use of immuno-cytochemical techniques increases diagnostic accuracy in these cases. Ghosh, Mason and Spriggs analysed 53 samples of pleural or peritoneal fluid from 41 patients with malignant disease. Conventional cytological examination had not revealed any neoplastic cells. Three monoclonal antibodies (anti-CEA, Ca 1 and HMFG-2) were used to search for malignant cells. Immunocytochemical labelling was performed on unstained smears, which had been stored at -20 °C up to 18 months. Twelve of the forty-one cases in which immuno-cytochemical staining