Background: Cytologic examination of serous effusions is an important diagnostic tool for the diagnosis of cancer, staging and prognosis of the patient. The newly proposed International System for Reporting Serous Fluid Cytopathology (ISRSFC) aims to standardize the cytologic reporting. Aim: The main objectives of our study were to reclassify serous effusion samples using the new International System for Reporting Serous Fluid Cytology (ISRSFC), compare cytological interpretation with histopathological diagnosis and/or clinico-radiological findings, to calculate risk of malignancy for each new category and to measure performance parameters.