Background: Neutrophils have been studied by several authors as an important cell that plays a major role in many inflammatory disorders such as asthma. It is known that neutrophil to lymphocyte ratio (NLR) is an important prognostic biomarker for many disorders especially bronchial asthma.
Objective: To assess the relation of NLR and bronchial asthma severity and to determine NLR discriminative performance between controlled and uncontrolled asthma.
Methodology: This case-control study was performed upon 80 asthmatic patients and 80 healthy controls. The asthma diagnosis was established according to GINA guideline. Asthma control test (ACT), spirometry test, total and differential leucocytic count were done and NLR was calculated for all studied subjects.
Results: A statistically significant differences were identified between asthmatics and healthy subjects regarding age, sex and history of other allergies(p < 0.001). NLR was statistically significantly higher in asthmatic patients compared to controls (p < 0.001). According to Receiver Operating Characteristic [ROC] curve, NLR could be used to predict asthma control at cutoff level > 1.32, with 92.5% sensitivity, 93.8% specificity, 93.7% positive predictive value and 92.6% negative predictive value. 
Conclusions: Neutrophil to lymphocyte ratio could be an important predictor biomarker for asthma control.