ABSTRACT Introduction: Organophosphate (OPC) and carbamate (CMC) compounds are highly toxic anticholinesterase (AntiChE) pesticides, extensively used worldwide, and still responsible for poisoning epidemics. Multi-organ dysfunctions have been reported following AntiChE poisoning. Aim: This study aimed to assess the correlation between poisoning severity score (PSS), Glasgow coma scale (GCS), and butyrylcholinesterase (BuChE) levels with clinical and laboratory changes in adult patients with acute AntiChE intoxication. Subjects and methods: This study included 25 individuals in healthy-control-group (HC-group) and 75 patients in AntiChE-group. According to poisoning severity criteria, patients were allocated into mild, moderate, or severe intoxicated-group. Gender, age, and causative substance data were reported. Clinical parameters like grade of PSS, delay in hospital arrival time (DHA), vital signs functions, GCS score, and length of hospital stay (LHS) were measured. The blood levels of biochemical parameters (pH, sodium, potassium, and random blood glucose) and enzymatic biomarkers (BuChE, cardiac creatine kinase-myocardial band and cardiac troponin I, pancreatic amylase and lipase, hepatic aspartate and alanine aminotransferases, and kidney urea and creatinine) were estimated. Results: Cases were mostly females, aged 23.82±0.82-year, and intoxicated by OPC, especially malathion. The commonest clinical findings were minor manifestations of PSS, DHA for 2-hour, drowsy GCS level, and relatively short LHS for ≤24-hour, while vital signs abnormalities predominantly included tachycardia, hypertension, tachypnea, and hyperthermia. The main biochemical abnormalities were metabolic acidosis, hypernatremia, hypokalemia, and hyperglycemia. Low BuChE levels were detected in all cases, whereas increased enzymatic biomarkers levels were noticed in some cases. On admission, the proportions and mean values of overall clinical and laboratory parameters showed statistically significant differences among the three intoxicated-groups and between AntiChE-group and HC-group. Additionally, PSS grade, GCS score, and degree of BuChE inhibition significantly correlated with DHA, all vital signs, LHS, and overall laboratory parameters as well as between each other. At discharge, the initial clinical and laboratory abnormalities were markedly improved and showed statistically insignificant differences from HC-group except for BuChE levelsremained significantly low. Conclusion: Although the PSS, GCS, and BuChE seem similarly useful clinical indices at predicting severity of AntiChE poisoning, however, the efficacy of PSS outperform the GCS and BuChE effectiveness.