It is valued that near 10-15% children have diagnosis of asthma up to 10 years old. Cigarette smoke breathing increases signs and it makes treatment of asthma difficult. It concerns equal active smoking as well as passive cigarette smoke breathing in. Cigarette smoke exposure can cause progress of chronic inflammatory states of respiratory tract and in consequence can lead to COPD or cause asthma exacerbation and more severe course of asthma. Negative results of smoking concern also pregnancy outcome and further child development. Near 30% of asthma treated patients admit smoking or is exposed on passive smoking. Similar percent of smokers can appear among pregnant women. Cigarette smoke exposed children have greater number of asthma exacerbations comparing to non exposed asthma children, they also have greater number of hospitalisations per year and need greater average dose of corticosteroids in standard treatment sustaining clinical symptoms remission. There is proved positive correlation between level of nicotine metabolite – cotinine in children urine and number of smoked cigarettes by their parents. Researches on cotinine levels in active and passive smokers urine show direct correlation with progress of respiratory tract pathology, particularly with more severe outcome and more difficult treatment of asthma. Cigarette smoke disturbs respiratory tract physiology, which effects with lesser response to classic corticosteroid asthma treatment and suggest including antileukotriene drug AT such patients due to modification of pathological influence on respiratory tract cigarette smoke toxic substances.