The aim of this study was to assess changes in the sense of coherence of patients who had suffered their first myocardial infarction. Out of 100 patients at the start of the study, these changes were evaluated in 66 men and 18 women aged 36-70 years. Generally, the sense of coherence was found to be stable among the whole group, but there were significant individual variations in its development in some of the participants over the following years. Even the individuals with an initally high sense of coherence could experience a decrease in its level. The changes that were found in the men can be explained by their marital status, level of treatment satisfaction, disease perception/quality of life, physical limitation, and alcohol intake and/or tobacco use at the baseline. An unexpected finding was that the single men with an initially high sense of coherence experienced a decreased level over time. In order to maintain or increase patients' sense of coherence, it is important for nurses to help them identify their risk factors and to provide conditions for individualized cardiac rehabilitation in order to avoid another myocardial infarction.