BACKGROUND: An adequate diagnosis of lung malignancy can be detected through examination of pleural fluid and Transthoracic needle aspiration (TTNA) based on the cell block method and tissue core biopsy. The cell block method is an immunocytochemical examination method that is useful for the adequate diagnosis of lung malignancy.
 AIM: This study was to compare the effectiveness of the cell block method with tissue core biopsy on pleural fluid cytology and TTNA cytology to establish the diagnosis of lung malignancy.
 METHODS: This study is a diagnostic test with an analytical cross-sectional approach on 15 respondents suspected of lung cancer at Dr. Moewardi Hospital Surakarta in September 2021. Subjects underwent pleural fluid cytology, TTNA cytology based on the cell block method, and tissue core biopsy examination. Data analysis used the Kappa test and bivariate analysis to calculate the p-value.
 RESULTS: The results of the combined examination of pleural fluid cytology and TTNA cytology based on the cell block method gave a very good level of conformity to the tissue core biopsy with a Kappa value of 0.857 and a p-value of 0.001. The results of the combined examination of pleural fluid cytology and TTNA cytology with cell block method showed the highest percentage for sensitivity (100%), NPV (100%), and accuracy (93%); while the results of the TTNA cytology examination using the cell block method showed the highest percentage of specificity (100%) and PPV (100%) of the tissue core biopsy method.
 CONCLUSION: The cell block method is very effective and significant in assessing the results of combined pleural fluid cytology and TTNA cytology against the tissue core biopsy method so that it is useful for the adequate diagnosis of lung malignant