Objective To explore the application value of paraffin embedding cell blocks from hydrothorax and ascite in diagnosis of tumors in the chest.Methods Of all clinical inspection for hydrothorax samples of thin-layer cytology,suspicious made paraffin embedding sediments of the tumor cells,immunohistochemical staining,identified the benign and malignant cells,determined the types of tumor cells and tissue origin.Results For liquid thin-layer cytology diagnosis of heterocyst,suspicious cases of malignant tumor,69 cases made the cell block combined with immunohistochemical staining,determined the malignant 51 cases,17 cases were benign,difficult to diagnose in 1 case,malignant determined the source of 46 cases,adenocarcinoma did not determine the source of 6 cases.Conclusion The technique of the embedding of paraffin embedding cells is of great value to the organization of the malignant and malignant tumors of the cells from hydrothorax and ascite.