Background Not much is known about the patients' decision time in acute coronary syndrome (ACS). The aim of the survey was therefore to describe patients' decision time and factors associated with this parameter in ACS. Methods We conducted a national survey comprising intensive cardiac care units at 11 hospitals in Sweden in which patients with ACS diagnosis and symptoms onset outside hospital participated. Main outcome measures were patients' decision time and factors associated with patients' decision time. Results In all, 1939 patients took part in the survey. The major factors associated with a shorter patient decision time were: 1) ST-elevation ACS, 2) associated symptoms such as vertigo or near syncope, 3) interpreting the symptoms as cardiac in origin, 4) pain appearing suddenly and reaching a maximum within minutes, 5) having knowledge of the importance of quickly seeking medical care and 6) experiencing the symptoms as frightening. The following aspects of the disease were associated with a longer decision time: 1) pain was localised in the back and 2) symptom onset at home when alone. Conclusion A number of factors, including the type of ACS, the type and localisation of symptoms, the place where symptoms occurred, patients' interpretation of symptoms and knowledge were all associated with patients' decision time in connection with ACS.