Background and Objective: A number of studies have reported a daily and yearly variation in the occurrence of acute myocardial infarction (AMI). It has been shown that the circadian variation of AMI is the result of an increase in the incidence of plaque rupture during the morning hours. These studies have shown a relation between the solar motion and the occurrence of AMI. Effect of lunar cycles on various medical illnesses like seizure and psychiatric disturbances are documented. However, there were a few reports conflicting result about relationship between lunar cycle and the occurrence of acute coronary events. The period it takes for the moon to orbit around the earth and the period of the lunar phase differ. Therefore, we investigated the relation between the occurrence of AMI and the gravitation of the moon. Methods: From 1996 to 2008, 1,034 consecutive patients with AMI from Gangneung Asan Hospital were included. The universal gravitation of the moon was calculated and compared to the earth onset time of AMI. Universal gravitation of the moon (UGm) was derived by G��m/d2 (G: universal gravitation constant: 6.67259 �� 10−11m3s−2 kg−1, m: mass of the moon, d: the distance between the center of the moon and the center of the earth). The relationship between Universal gravity and the cases of AMI were determined. Results: The lunar days were not related with the Universal gravitation of the moon and the occurrence of AMI. However, the occurrence of AMI was increased when a distance more than 394,155 km or Universal gravitation less than 33.5 between the earth and the moon. Conclusion: These results suggest that the Universal gravitation of the moon may relate to the occurrence of AMI. Further investigation for the relationships and mechanisms between the Universal gravitation of the moon and cardiovascular system were needed.