January 2023—In recent years, a standardized classification system for the cytology of serous body cavities has been proposed. The system, known as the International System for Reporting Serous Fluid Cytopathology (ISRSFC), published by Ashish Chandra, et al.,1 in 2020, aims to enhance the reproducibility of cytologic diagnoses, thereby facilitating clearer communication with clinicians. The diagnostic categories are as follows: I. Non-Diagnostic; II. Negative for Malignancy; III. Atypia of Undetermined Significance; IV. Suspicious for Malignancy; V. Malignant. Each progressive diagnostic category from I through V carries with it an increasing risk of malignancy. This brief review article aims to highlight the salient points of each diagnostic category and includes discussion of recent publications and our own institutional experience.