Introduction Asthma is a chronic inflammatory disease of the respiratory system that results in a reduced airflow exhaled by respiratory tract, accompanied by a group of characteristic clinical symptoms: cough, dyspnoea, chest tightness and wheezing. Asthma, due to the course and treatment process, may modify the quality of life (QoL). Assessment of the quality of life in patients with asthma, including the degree of disease control, Body Mass Index (BMI) and ciggaret smoking. Material and methods The research was carried out among 124 patients with asthma. Data were collected by Internet using a diagnostic survey method consisting of the author’s questionnaire, the Asthma Control Test (ACT) and Saint George’s Hospital Questionnaire (SGRQ). The results were processed in the R program. In statistical analysis Spearman’s rho, Anderson-Darling test (Test AD), Mann-Whitney U test and the Kruskal-Wallis test were used. Statistical significance was accepted for p ≤ 0.05. Results Research results showed a deterioration in the quality of life of asthmatics. People with better disease control had a significantly higher quality of life. Patients with a higher BMI had a significantly lower quality of life (“Symptoms”, “Impact on life” domain, global score). Smoking cigarettes did not influence the quality of life. Conclusions Determinants of worse quality of life in asthma patients are primarily: poor control of the disease and a high BMI.