Background. The coronary artery bypass graft surgery (CABG) serves the improvement of blood supply of the heart muscle. Better blood supply augurs the improvement of cognitive functioning in surgically operated persons. The patients who have undergone these kind of operations, in fact are endangered with unfavourable working factors, connected with different techniques of intervention. Many studies have suggested the generalised and unspecific deterioration of cognitive functioning after CABG. Aim The aim of our research was the assessment of the cognitive processes (the recognition of visual items, thinking abstract, the verbal fluency) as well as subjective opinion of one's own memory in cardiac surgery patients, and qualification of clinical and individual variables which could influence on pre- and post-surgical cognitive functioning. Methods. The group consisted of 18 patients (9 women, 9 men), at the age of 55-81 years. The psychological assessment was executed twice - before and after operation. In the psychological assessment, the following were used: the Benton test of Visual Memory, verbal fluency (Animals, Supermarket), subtest Similarities (WAIS-PL) as well as the Questionnaire of Opinion of Efficiency Own Memory Giovagmoli. Results. The patients receivedhigher results in the majority of cognitive tasks in the second (postoperative) investigation, in this especially, in estimating the ability of recalling the words (verbal fluency - Animals; Supermarket) as well as abstract thinking (Similarities). Conclusions. The cognitive functioning of patients treated with the use CABG improved in several days after the operation in relation to their state before intervention. Higher results were noted in tasks of abstract thinking as well as verbal fluency. The clinical and individual factors modify the patients' results in various degrees.