Primary percutaneous coronary intervention (PCI) is at present the most effective procedure for reducing the mortality rate of patients with acute myocardial infarction (AMI). However, there is a great difference between Japan and other countries in the rate of primary PCI.Registration period, number of patients with AMI, rates of primary PCI or thrombolysis and in-hospital or 30-day mortality rates were analyzed in 3 Japanese, 4 European, 4 American and 2 world-wide databases of AMI. The primary PCI rate is higher (75-94%) in Japan than in the other countries (5.5-49.6%), particularly in low-volume hospitals, and the mortality rates at these centers were similar to those in high-volume hospitals (approximately 4-10%). The primary PCI rate has recently been rising (25-50%) worldwide and most PCI procedures are performed in large-volume centers, except in Japan.Comparison of the AMI databases suggest there is a relationship between the primary PCI rate and annual PCI caseload in each country. It is interesting that in Japan even low-volume PCI hospitals have comparable numbers of primary PCI cases.