TITLE: Correlation of subjective experience and objective parameters of the severity of heart valve disease OBJECTIVE: The aims of this research are to find out if there is a congruency between the subjective perception of an illness and the objective parameters of the severity of the illness; to examine the ratio of agitation without a relevant basis- overestimation of the illness; to research the degree of underestimation of one’s illness – lack of criticism and rejection of the illness with inappropriate behaviour. STUDY DESIGN: cross-sectional study PARTICIPANTS AND METHODS: 60 participants with heart valve disease treated in the Polyclinic Kardioton participated in the study. A questionnaire was used to collect subjective data. The questionnaire comprised demographic data including sex, age, marital status, work status, education and 38 items eliciting illness perception. A five-point Likert-type scale of agreement accompanied each of the 38 statements (1-strongly disagree, 5-strongly agree). The questionnaire was adapted from the IPQ-R (Revised Illness Perception) questionnaire and translated to Croatian. The objective data is based on the medical diagnosis of the Doppler echocardiographic parameters. The questionnaires were collected in the period of January through August 2018. The participants were divided into 3 groups, depending on the severity and diagnosis of their illness. RESULTS: Out of 60 participants, 30 are part of the “A” group with less difficult diagnoses, 20 are part of the “B” group with moderate diagnoses, and 10 are part of the “C” group with difficult diagnoses. Most of the participants (40) would rate their illness as “moderate”, 13 consider their illness to be “difficult”, and 7 consider it to be “less difficult.” Compared to the objective data of each of the participants, most of them (31) overestimate their illness. CONCLUSION: Conclusion: There is a congruency between the subjective perception of one’s illness and the objective parameters of the severity of the illness. 51,7% of the participants, the largest number overestimate their illness, 36,7% of them perceive it realistically or in congruence with the objective parameters. 11,6% of the participants underestimate their illness, i.e., they perceive it to be less difficult than it actually is.