Background: Acute organophosphorous poisoning (OPP) is a fatal medical emergency necessitating rapid evaluation plus aggressive management. Aim of the study: Assessment of white blood cell/ platelet ratio (WPR) role in predicting severity and outcome of acute OPP patients. Subjects and Method: A retrospective study; implemented on acute OPP cases who were presented to Zagazig University Hospitals and Zagazig Poison Control Unit over one year. Data were gathered from patients' records including full history, clinical examination findings and investigations requested. Patients were categorized according to their fate into two groups; good and poor outcome. Results: Out of the 89 cases with confirmed OPP, 79 (88.7%) signified good outcome cases while 10 (11.3 %) were bad outcome. Most cases (69.7%) were in age group (20-40). Females were predominant (57.3%). Suicidal route, CNS toxicity were dominant in poor outcome group. Intermediate syndrome, poison severity score, lactate, white blood cell count, WPR, ICU admission and needing mechanical ventilator were significantly high while Glasgow coma scale, PH, mean arterial blood pressure, pseudocholinesterase and platelets were significantly low in the poor outcome group. Best cutoff value of WPR was ≥0.106, sensitivity 100%, specificity 74.7% and accuracy 77.5%. The area under curve (0.848) revealed high significance. Conclusion: Patients with a high WPR had the worse outcome. WPR is determined to be the most significant correlated predictor with other predictors of poor outcome as low GCS and high PSS. Recommendation: WPR could be recommended as a simple and applicable biomarker to predict severity and outcome of acute OPP.