The evaluation of serous effusions is essential in cytopathology due to their diagnostic and prognostic significance. The lack of material for adjuvant diagnostic investigations, such as immunocytochemistry and cytogenetic study, is a major drawback of the standard cytological smear. The cell block method helps you avoid this limitation. It is made from sediment cells that are converted into solid compact pellets, which helps in studying tissue architecture and applying further immunohistochemical studies. The use of cell block (CB) as an adjunct to routine cytology smears of body fluids can increase the sensitivity to a considerable extent. Aim: Aim of the work to apply different cell block techniques on effusion samples (pleural and peritoneum) and correlate them to reach the best cell block techniques which give the highest diagnostic scores and accuracy. Patients and Methods: This was a prospective analytic comparative study conducted at the Department of Pathology, Qena University Hospital (in the period from March 2021 to December 2022). Results: Agar-based cell block showed the highest accuracy (93.33%) followed by formalin/ ethanol fixative (7 parts of 100 percent ethanol/ 3 parts of 100 percent formaldehyde) cell block (86.67%) in effusions. Cytology showed the least accuracy (80%), Conclusion: We advocated using of cell block technique with cytological cases, because of its great benefit in raising the accuracy of diagnosis for different cytological samples. we proved that Agar-based cell block showed the highest scores and the highest diagnostic accuracy in effusion samples. It shows better results for texture, intensity, and number of cells when we use mixture of 5 parts of 95 percent ethanol/ 5 parts of 10 percent formaldehyde as a fixative solution in this method. And Formalin/ ethanol fixative (7 parts of 100 percent ethanol/ 3 parts of 100 percent formaldehyde) based cell block came in the second place in its scores and diagnostic accuracy. But the egg albumin-based cell block and the plasma thrombin based cell block have the least score and the least diagnostic accuracy in effusion samples.