Introduction: Slides without clinical history can influence diagnostic interpretation accuracy, contributing to mis- diagnosis and impair consistency. The goal is to evaluate the new screeners’ performance through blinded cytology screening of thyroid FNAC cases by demonstrating reliability and diagnostic accuracy between inter-and intra-ob- servers. This study conducted a correlational research design at Cytology Laboratory, Faculty of Health Sciences, Universiti Teknologi MARA (UiTM) Selangor, Malaysia. Methods: Five new screeners were chosen to blindly screen slides without unprovided clinical history to measure competency. Diagnoses were obtained using a light micro- scope from two screening sessions, with 40 cases, respectively. The inter-and intra-observer reliability testing was measured using the kappa value of Fleiss’ and Cohen’s kappa value, respectively, while the diagnostic accuracy without a clinical history was determined by the receiver operating characteristic (ROC) curve. Results: The in- ter-reliability kappa value (multiple new screeners) unveiled as ‘Fair’ agreement (κ) = 0.598, while intra-reliability (single new screener) showed ‘Almost Perfect’ agreement with (κ) = 0.856. The overall diagnostic accuracy was an average of 83.50 %, and the area under the curve (AUC) of ROC was 0.837 (83.7%). Operating parameters show an average value of 87.38% for sensitivity, 79.98% for specificity, 81.26% for positive predictive value (PPV), 86.62% for negative predictive value (NPV), and 23.73 for likelihood ratio (LR). Conclusion: Most new screeners have ample knowledge and skills in cytological screening. This blinded screening could be a practice to access a new screener’s true ability in the future.