The examination of cognitive function is not the part of the basic set of tests which is carried out in patients with chronic obstructive pulmonary disease (COPD). However there are some theoretical reports and sparse publications indicating the impairment of these functions among patients with COPD. These impairments are related to the patients with hypoxemia. In non-hypoxemic patients with COPD cognitive performance should be studied because of controversial reports. The influence of COPD on cognitive performance is partially reversible using oxygen therapy and/or physical activity which, in our opinion, is not appreciated enough. It seems that evaluation of cognitive performance with selected tests can be helpful in the assessment of severity of the disease. Moreover, it can be useful in estimation and prognostication of the self-dependence degree as well as the patients life span. The use of such methodological tools as corresponding tests analyzing cognitive performance in patients with COPD could lead to better care. It could also minimize the risk of transition of mild cognitive impairment into dementia which results in significant quality of life deterioration. It appears that patients with present impaired cognitive performance with or without recognized dementia should remain under special care providing adequate treatment. We assumed that due to properly managed treatment it may be possible to retain the process of increasing cognitive impairment what would effect in long-term self-reliance.