Objectives: To evaluate variation of the level of H-FABP in patients with acute myocardial infarction before 6 hours and after 24 hours; to define the relationship between the level of H-FABP and Killip class & early complications in acute myocardial infarction. Patients and methods: The prospective, cross-sectional study was conducted in 62 patients with acute myocardial infarction (AMI) hospitalized before 24 hours since symptom onset at Da Nang hospital. The study started in June 2013 and ended in June 2014. Results: The study carried out in 62 patients with AMI showed that the disease was more prevalent in patients aged over 60 years (58.1%). The average age to get this disease ranged within 65.74 ± 2.63, among which the number of male patients accounted for 74.2%, 25.8% higher than the females. The number of patients admitted to hospital before 6 hours and after 6 hours made up 30.6% and 69.4%, respectively. For the group hospitalized before 6 hours, H-FABP became detectable very soon in serum (less than one hour) and increased rapidly in most cases. The median levels of H-FABP recorded at1-6 hours were 157.75±55.64 ng/mL, peaked at 384.82±98.4 ng/mL at 7-12 hours and returned to normal at 4.75±0.9 ng/mL after 36 hours. There was a positive correlation between the level of H-FABP and early complications of AMI. The level of H-FABP rose gradually with the degree of heart failure (51.46±15.7 ng/mL in Killip class I, 136.70±43.9 ng/mL in Killip class II, 138.10±30.4 ng/mL in Killip class III, 818.65±422.2 ng/mL in Killip class IV). The level of H-FABP also increased gradually together with the severity of complications (acute mechanical complications (79.95±53.6 ng/mL), recurrent myocardial infarction (84.61±25.6 ng/mL), arrhythmias (161.09±31.3 ng/mL), heart failure (143.11±25.4 ng/mL), cardiogenic shock (175.63±39.4 ng/mL), sudden death (180.77±68.4 ng/mL). The more complications patients had, the higher their level of H-FABP (the levels of H-FABP were at 28.78±45.3 ng/mL for the group of patients without complications, at 112.48±74.3 ng/mL for those with one complication, at 147.29±201.9 ng/mL with two complications, at 173.74±120.1 ng/mL for those with three complications and at 238.06±382.5 ng/mL for those with four complications). Conclusions: The study revealed the important role of H-FABP in early diagnosis of AMI and also demonstrated its importance in providing valuable prognostic information on post-AMI events. Key words: H-FABP, acute myocardial infarction