Introduction: Poisoning with Organophosphorus (OP) compounds is a common toxicological emergency in an agricultural country like India because of its ease of availability. Fatality in organophosphorus toxicity is mostly due to respiratory failure and cardiovascular collapse. Studies have shown that respiratory failure is one of the most common complications in the acute stage. Objectives: The aim of this study was to assess the effectiveness of Glasgow Coma Scale (GCS), Poisoning Severity Scale (PSS) and Peradeniya Organophosphorus Poisoning (POP) Score in predicting the development of acute respiratory failure following Organophosphorus compound poisoning. Materials and methods: A prospective, observational study was carried out over a period of one year from July 2017 to June 2018. The diagnosis was based on history of exposure to organophosphorus compound, along with symptoms and clinical signs of cholinergic crisis. Patients were followed up for 24 hours after the exposure to OP compound and were examined for development of acute respiratory failure. Results: Out of the total 110 patients in the study, 61(55.45%) were males and 49(44.54%) were females. The mean age was 30.03 +10.242 years. Twenty-nine (26.36%) patients developed acute respiratory failure. Patients with GCS less than 10, PSS of 3 or more and POP scale of moderate and severe poisoning more commonly developed acute respiratory failure. Conclusion: A low GCS (<10), PSS of 3 or more and a POP grade of moderate and severe poisoning had a strong association with the development of acute respiratory failure.