Abstract: Objective To investigate the changes of peripheral blood neutrophil-lymphocyte ratio (NLR) and plateletlymphocyte ratio (PLR) in patients in acute stage of bronchial asthma and their clinical significance. Methods A total of 262 patients with acute asthma, including 97 critical and 175 non-critical patients, were recruited from our hospital between January, 2013 and May, 2016, with 130 healthy individuals as the control group. The absolute neutrophil count, absolute lymphocyte count, platelet, NLR and PLR were compared among different groups, and their diagnostic values were evaluated using the area under the receiver-operating characteristic (ROC) curve. Results The absolute neutrophil count, absolute lymphocyte count, PLR and NLR (P<0.0001), but not platelet count (P=0.971), differed significantly among the 3 groups. The absolute lymphocyte count was significantly lower while the absolute neutrophil count, NLR and PLR were significantly higher in asthmatic patients in critical condition than in patients in non-critical condition and the control subjects (P<0.0001), and these parameters showed no significant differences between latter two groups (P>0.05). The areas under the curve of absolute neutrophil count, absolute lymphocyte count, NLR and PLR for the diagnosis of acute exacerbation of bronchial asthma were 0.802, 0.784, 0.873 and 0.795, respectively (all P<0.01); the optimal cut-off value of NLR was 2.58 for the diagnosis with a sensitivity of 82.8% and a specificity of 81.1%. Conclusion Peripheral blood NLR and PLR are increased in asthmatic patients, and their variations offer assistance in the diagnosis and assessment of bronchial asthma.