Objectives: Cytological examination of serous fluids is of paramount importance in detecting cancer cells. Distinguishing malignant cells from benign reactive mesothelial cells in fluid cytology is an everyday diagnostic problem. Cell blocks are valuable when the features in cytology are inconclusive. The motive of this study was to assess the utility of this method in increasing the diagnostic yield of serous fluids. Methods: 225 (25%) effusion fluids were analyzed carefully by both smear and cell block technique. Results: Among 225 fluids, 139 were pleural, 84 peritoneal and 2 pericardial. In case of pleural fluids and ascitic fluids, maximum numbers of cases were inflammatory. By the cell block technique, 5 additional cases of malignancy in pleural fluids and 7 additional cases of malignancy in ascitic fluids were diagnosed which could not be detected in the cytological smears. In pericardial fluids both cases were inflammatory. Male predominance was noted in case of pleural effusion and female predominance was noted in case of pericardial effusion and ascites. Maximum numbers of cases were seen in the age group of 40-60 years. Conclusion: We conclude that the cell block technique when used as an adjuvant to routine smear examination has increased the diagnostic yield because of better preservation of the architectural pattern.