The aim of the work was to carry out expert assessment of complexity of operations and to study interrelationship of the average score of complexity of the interventions with lethal outcome and duration of treatment in the Intensive Care Unit (exemplified by comparison with the outcomes of operations on cardiac valves performed in 2009 in the setting of artificial circulation in adult patients). Complexity was assessed by a total of 13 cardiovascular surgeons specialized in operations aimed at correcting valve defects (4 of them were from the A. N. Bakulev Scientific Centre for Cardiovascular Surgery), with none of the participants being aware of the therapeutic outcomes of each type of the operation performed. An average expert-defined score was assigned for each of the 33 names of the operations. The Kendall coefficient of concordance for all operations amounted to 0.29 (p<0.001); consensus in the complexity-score (from 69 to 85%) was achieved for 48.5% of the operations thus considered. The values of the mean scores of complexity of operations, defined by the specialists form the SCCS (2.02±0.54) were significantly lower (Wilcoxon's test; p<0.001) as compared with the average score assigned by specialists from other facilities (2.28±0.43). The duration of the stay at the ICU of the patients subdivided into groups depending on the expert score was found to differ significantly (p=0.007). The area under the ROC curve using the EuroSCORE (0.59) is suggestive of its lower accuracy in assessing the lethal outcome as compared to the expert score (0.68). The obtained findings strongly suggest advisability of using expert score of operations' complexity for solving complicated non-formalized tasks on allied problems of cardiovascular surgery and organization of public health care (accrediting of medical facilities, formation of the government order, and planning of the budget of medical facilities).