Organophosphorus pesticides are considered a major human health concern, primarily in developing countries. Acute toxicity of these compounds is known to have serious health consequences. The study aimed to assess the role of cholinesterase enzymes (acetylcholinesterase and butyrylcholinesterase) as predictors for severity following acute OP intoxication immediately after admission, using Peradeniya Organophosphorus Poisoning (POP) clinical severity scoring. It was conducted on fifty patients recruited from Mansoura University Emergency Hospital with history of acute exposure to organophosphorus compounds (OPCs). Detection of OP toxicity was done using thin layer chromatography (TLC) technique; assessment of severity of OP poisoning was done using Peradeniya Organophosphorus Poisoning (POP) scale; and estimating ACHE and BuCHE levels that was done using microlab auto-analyzer. No statistically significant associations were found between initial ACHE enzyme levels and POP severity scoring (p=0.075), meanwhile, initial BuCHE levels were significantly associated with POP severity scoring (p=0.045). Thus, measurement of BuCHE enzyme on admission is a sensitive biomarker for acute OP exposure and severity. Although ACHE enzyme is considered a specific biomarker for diagnosis of OP toxicity, it cannot be considered a sensitive biomarker for severity.