Introduction: Delayed neurological sequelae (DNS) are the most frequent morbidity after acute carbon monoxide (CO) poisoning. Therefore, their prevention and early prediction are the main goal of treatment. Aim of the work: This study aimed to investigate parameters based on peripheral complete blood cell count (CBC) as predictors of DNS in acute CO poisoning. Methodology: It included 67 acutely CO poisoned patients and 38 healthy volunteers. On admission, history, clinical examination and routine laboratory investigations were done. Ratios based on CBC counts were measured. Patients were followed up along 6 months for DNS signs. Results: The results revealed that total white blood cells (WBC) count, absolute neutrophil count & percentage and median values of neutrophil-lymphocyte ratio (NLR) & systemic immune inflammation index (SII) were significantly higher while lymphocytes percentage, absolute monocytic count and percentage were significantly lower in CO poisoned patients compared to control group. DNS-complicated patients had significantly lower total WBC count, absolute neutrophil count & percentage and significantly higher median values of NLR and SII than non-complicated. Based on receiver operating characteristic analysis (ROC), NLR and SII were significant predictors of DNS. Conclusion: It was concluded that, NLR and SII ratios may be helpful predictors of DNS after acute CO poisoning.