Viral infections augment immediate and late allergic responses in the lungs of patients with allergic asthma. Certain viruses that typically exacerbate asthma have been noted to induce release of the cytokine interleukin-11 (IL-11) which is associated with airway hyperreactivity (AHR). The aim of study: To determine the frequency of influenza-like illness in patients with allergic asthma on immunotherapy compared to the patients with allergic asthma receiving only antiasthmatic pharmacotherapy during the period of 1-year follow up. Methods: In our study, we included 60 patients with allergic asthma, both genders who were subsequently divided into two treatment groups. Study group included 30 patients who received immunotherapy (immunotherapy group) and control group included 30 patients treated with standard pharmacotherapy, but not with immunotherapy (GINA proposal). Results: There was a significant difference in influenza-like illness (ILI) between immunotherapy and control group of patients. A significantly higher percentages of patients in control group experienced cold and/or flu syndrome compared to immunotherapy group, which was observed at the 2nd, 3rd and 4th trimester (X2= 20.480 p=0.0001). During the first trimester there was no difference in the number of patients with the cold/flu symptoms between the immunotherapy and control group. During the 2nd trimester, there was a significant decrease in the number of patients with cold/flu symptoms 3/30 (10%) in the immunotherapy group, while in the control group there was significantly higher number of patients with the cold/flu symptoms (11/30 (36 %)). In the 3rd and 4th trimester the frequency of patients with cold/flu symptoms was unchanged compared to the 2nd trimester in the immunotherapy group, while in the control group the frequency of patients with cold/flu symptoms increased from 20/30 (66%) at the 3rd to 27/30 (90%) in the 4th trimester. The number of patients reported to the physician due to bronchial hyperreactivity was dependent on the immunotherapy treatment (p=0.0001) Conclusions: The frequency of influenza-like illness occurrence was significantly lower in patients treated with immunotherapy during one year of follow-up compared to the patients treated with antiasthmatic pharmacotherapy. The percentage of patients with influenza-like illness was 10% in the patients treated with immunotherapy at third and fourth trimester of the follow-up, whilst in patients on antiasthmatic pharmacotherapy, the percentage of patients with influenza-like illness increased from 66% in the third to 90% in the fourth trimester.