Readjustment after an event of coronary heart disease (CHD) is defined to comprise cognitive, instrumental and affective components. The cognitive dimension refers to understanding of the disease. Twenty-three patients (<60 years) with CHD were interviewed about the nature of their disease and encouraged to use their own words. The study was conducted 1 year after the event of myocardial infarction (MI) and some patients had also been revascularized. The interviews were transcribed in extenso and analysed according to the phenomenographic approach. The main finding was the great variation of conceptions revealed. Six different conceptions were found concerning CHD. Some patients comprehended MI by involving (A) blood and vessels, (B) either blood or vessel or referred to (C) risk factors/symptoms. Angina pectoris was expressed as (A) insufficient heart capacity, (B) atherosclerosis/contracted vessel or as (C) symptoms. Several patients found it difficult to expand their answers and some expressed misconceptions about the course of events. Patients' pre-existing knowledge and their way of reasoning about central phenomena related to their disease should be taken into consideration in patient education and is also applicable in individual encounters with patients.