BACKGROUND Patients affected by acute coronary syndrome (ACS) report several symptoms subsequent to their discharge from hospital. These symptoms prolong their sick leave and complicate their return to the normal activities of everyday life. To improve health outcomes and establish quicker recovery for these patients, there is a need to better understand patients' perceptions of their illness. OBJECTIVE To explore patients' experiences of ACS during their hospital stay. METHODS A qualitative interpretative interview study was conducted among patients during their hospitalization for ACS. METHODS The study was performed in two designated coronary care units at a hospital in Sweden. METHODS Twelve participants (five women and seven men; age range, 45-72 years), hospitalized with a diagnosis of ACS, were included in this study. METHODS Patient narratives were recorded and transcribed. The records were later analyzed using a phenomenological hermeneutic approach. RESULTS Patient experiences of ACS were formulated into one main theme: "awareness that life is lived forwards and understood backwards". Two minor themes predominated in this main theme. The first was a sense of "struggling to manage the acute overwhelming phase", which included four sub-themes: onset of life-threatening symptoms; fear and anxiety; being taken by surprise; and experiencing life as a hazardous adventure. The second theme was "striving to obtain a sense of inner security", which also included four sub-themes: searching for and processing the cause and its explanation; maintaining a personal explanation; dealing with concern and uncertainty; and having a readiness to negotiate with life-pattern activities. CONCLUSIONS Hospitalized patients affected by ACS consider the cause of the onset and prepare to optimize their future health. These patients construct personal models to explain their disease, which may persist throughout continuum of care. One way to improve health outcomes for patients with ACS is to establish a shared knowledge about the illness and formulate personal care plans that cover the hospital stay as well as possibly extending into primary care after discharge, based on the patients' point of view.