OBJECTIVES: Understanding and identifying impaired quality of life (QoL) is now recognised as an important component of asthma and COPD management. The aim of the study was to assess which factors affect patient’s QoL, to examin the relationship between these factors (outcomes) and the QoL data; as well as to evaluate the possible differences between patients with and without a significant high level of anxiety/ depression. METHODS: A total of 130 patients (70 asthmatics and 60 COPD) were analysed in the study. Patients were asked to respond to self administered questionnaires: the St George’s Respiratory Questionnaire (SGRQ), the EQ-5D, the Beck depression scale and a range of questions concerning smoking habits, inhaler use technique, disease management. Data was analysed by using Statistical Programme Package for Social Sciences statistical software 15.0; linear multiple regression and factor analysis were conducted. RESULTS: We found at 5% significance level notable correlation between the SGRQ score and EQ-5D -0,648; Beck score 0,690; FEV1 0,522; age 0.505. We implied a linear multiple regression model, where the dependent variable was the SGRQ score and the independent variables were: FEV1 and the Beck score (R2=0.48; P=0.001) in model 1; and disease severity/ hospitalisation and Beck score (R2=0.55; P=0.005) in model 2. In the factor analysis the loading of the 9 outcomes (age, sex, anxiety/depression, smoking status, lung function, disease severity/hospitalization, inhaler use technique, disease management) onto 5 identifiable factors suggest that, patients actual health status is mainly affected by age, sex, the Beck scale (depression) and smoking. CONCLUSIONS: Our results suggest that however correlation is moderately strong between QoL and clinical outcomes, patients QoL impairment is mainly attributable to depression status, inhalation technique and smoking status. All of these can be improved by adequate, regular patient education, resulting in optimal asthma and COPD control.