Abstract. Illness perception is a concept that reflects patients' emotional and cognitive representations of disease. This study assessed the illness perception change during 6 months in 195 patients (33% women and 67% men) with acute coronary syndrome, taking into account the biological, psychological, and social factors. At baseline, more threatening illness perception was observed in women, persons aged 65 years or more, with poorer functional capacity (New York Heart Association [NYHA] class III or IV) and comorbidities ( p < .05). Type D personality was the only independent factor related to more threatening illness perception (βs = 0.207, p = .006). At follow-up it was found that only self-reported cardiovascular impairment plays the role in illness perception change (βs = 0.544, p < .001): patients without impairment reported decreasing threats of illness, while the ones with it had a similar perception of threat like at baseline. Other biological, psychological, and social factors were partly associated with illness perception after an acute cardiac event but not with perception change after 6 months.