This study aims to examine the impact of length of stay, hospital characteristics, physician characteristics and other factors on the expenditures of hospitalization for acute myocardial infarction (AMI) under Taiwan's National Health Insurance program. This study uses data collected from the Taiwan's National Health Research Institute's 2001-2003 National Health Insurance Research Database. We estimated contributors to increased expenditures of hospitalization using three-stage least square regression model. The hospital expenditures for the treatment of AMI averaged NT$126,366 (US$3829, US$1=NT$33) per discharge, with the largest proportion (27%) spent on room expenditures. They were strongly impacted by length of stay, increasing around 4.8% per day. We conclude that hospital expenditures for the treatment of AMI patients may vary widely depending on the characteristics of the hospital and physicians that provide them care.