The immune system is directly involved not only in the elimination of the pathogen, but also in the development of the main complications of the disease. In case of massive Toxocara canis infection, immune dysfunction after repeated infestations can lead to the development of chronic diseases, especially of the respiratory system [Tobin E.H., et al., 2011]. The purpose of our study was to analyze the immunological reactivity of patients with bronchial asthma in combination with toxocariasis, depending on duration of the disease and the age of patients. The study included 52 patients with pathology of the respiratory system (bronchial asthma, obstructive bronchitis) of different age and sex, who were divided into two groups according to the age. The first group involved patients over 40 years old (23 patients), the second group involved patients younger than 40 years (29 patients). The leukocyte formula was determined in all patients and the leukocyte index of intoxication Kalf-Khalif was calculated. The content of IgE and IgG antibodies to Anti-Toxocara canis was determined by ELISA. All patients received the antiparasitic treatment with albendazole and immune corrective therapy with BioR or polyoxidonium. The values of this parameters were expressed in M ± ES. The analysis of research data showed that the patients of the older group and with chronic diseases have a tendency to higher content of leukocytes (5,8±0,45 before the treatment and 5,2±0,44 after the treatment) than in the younger group of patients (5,0±0,28 and 4,8±0,24 respectively). Also, the older group of patients had the tendency to higher content of segmented neutrophils (51,6±2,76 before the treatment and 47,0±1,96 after the treatment), whereas the lower levels of segmented neutrophils were observed in the group of younger patients and they have been significantly decreased in dynamics (49,6±1,88 and 43,9±2,15 – p<0,05). The content of band neutrophils had a tendency to increase, contrary, in the younger group – 6,6±0,97 before the treatment and 5,4±0,75 after the treatment; the older group – 5,6±1,03 before and 5,3±0,74 after the treatment, it suggests about more pronounced «left shift» in leukocyte formula in patients of the younger group. This is confirmed by leukocyte index of intoxication Kalf-Khalif, which was lower in the older group (0,61±0,060 before and 0,67±0,040 after the treatment). This index before the treatment in the younger group was at the same level as in the older group and it was significantly increased after the treatment (0,88±0,095 – p<0.05) and was significantly higher than in the older group after the treatment (p<0.05). The content of eosinophils before the treatment had a tendency to increase in the older group of patients; the content of eosinophil after the treatment was decreased in both groups. The IgE content was at the same level before the treatment in both groups, after the treatment was a significant decrease in both groups (178±26.6 before the treatment and 111±18.5 after the treatment – p<0.05 in patients of the older group), and this decrease was more pronounced in patients of the younger group (171±26.1 before the treatment and 84±11,3 after the treatment p<0.01). The IgG antibodies to Anti-Toxocara content before the treatment had a tendency to increase in patients of the older group compared with patients of the younger group (41,5±3,66 and 35,0±2,92, respectively). The parameters of IgG antibodies to Anti-Toxocara content after the treatment in the first (older) group continued to remain significantly higher than in the second (younger) group (31,7±3,89 and 22,±2,57, respectively, p<0,05). Thus, the studied parameters suggest about more acute course of the disease in the group of younger patients and about more effective changes of the parameters after the treatment.