The study was done to determine the levels of changes in haematological parameters in patients with asthma in Southeast, Nigeria. A total of 200 subjects were recruited for the study comprising 100 subjects each for Patients with asthma (50 subjects were Males, 50 were Females) and 100 subjects for apparently healthy subjects (Control) (50 subjects were Males, 50 were Females) drawn from a tertiary health institution. About 3ml of venous blood was aseptically collected from the antecubital vein of each subject by standard technique and was dispensed into an EDTA bottle for haematological parameters determination. The haematological parameters were determined using Mindray BC-5300. The results were expressed as mean± standard deviation. The data were analysed with the statistical package for social science (SPSS) version 21 using t-test, ANOVA and the level of significance was set at P<0.05. The study showed increase (P<0.05) in WBC( 9.63±4.51 X109/L , 4.88±0.19 X109/L, P=0.047), decrease (P<0.05) in MCV (85.26±4.20fl, 90.01±0.05fl, P=0.035) , MCH (27.54±1.09 pg, 30.00±0.17pg, P=0.001), MCHC (325.20±4.97g/l, 333.34±0.07 g/l, P=0.006) and no significant difference (P>0.05) in Neutrophils (70.02±9.44%, 66.40±3.56%,P=0.446), Lymphocytes(28.38±10.20%,31.39±3.88%,P=0.554),Monocytes(1.50±0.50%,1.70±0.45%,P=0.524),Eosinophils 0.53±0.23%,0.51±0.45%, P= 0.959), Red blood cell (4.82±0.39 X1012/L, 5.04±0.51 X1012/L, P=0.435), Haemoglobin (13.78±1.36g/dl,15.13±1.52g/dl,P=0.175), Packed cell volume (41.60±3.78%,45.40±4.56%,P=0.189) and Platelets(255.40±58.16X109/L, 222.00±37.01X109/L, P=) of patients with asthma relative to control. The results showed decrease (P<0.05) in Neutrophils (60.50±3.54%, 76.37±4.56%,P= 0.026), Monocytes (1.00±0.01%,1.83±0.29%,P=0.030), increase (P<0.05) in Lymphocytes (38.50±2.12%,21.63±5.92%, P=0.034), MCH (28.60±0.28pg, 26.83±0.65pg, P=0.040), and no significant difference (P>0.05) in WBC (7.76±3.05, 10.86±5.51, P=0.533), Eosinophils (1.09±0.29%,0.1