The volume of percutaneous coronary interventions (PCI) performed in a hospital has been suggested to correlate with favorable outcomes in patients undergoing primary PCI for acute myocardial infarction (AMI). However, studies that use current data and compare treatment and outcomes for AMI among hospitals with different volumes are still limited in Japan. Between January 2004 and March 2006, 401 AMI patients underwent primary PCI in the 11 hospitals participating in the Ibaraki Coronary Artery Disease Study (ICAS). Clinical characteristics, treatment, and in-hospital outcomes were retrospectively compared between 254 patients admitted to high-volume PCI hospitals and 147 patients admitted to low-volume hospitals. Low-volume hospitals had a higher prevalence of multivessel disease patients. High-volume hospitals had longer onset-to-door times, which were offset by faster door-to-balloon times. Rates of coronary stent use and successful PCI were comparable between the groups. Low-volume hospitals more frequently performed intra-aortic balloon pumping. Length of stay was longer in low-volume hospitals, whereas in-hospital mortality, bypass surgery, and repeat PCI rates did not differ between groups. Although the present study assessed limited data based on small sample size, we observed that contemporary standard treatments including stent implantation were performed for AMI patients undergoing primary PCI in hospitals with both high and low case volumes. We did not find an obvious relationship between hospital PCI volume and in-hospital outcomes in our data. However, further prospective surveys should be attempted to confirm these results.