Objective To analyze inpatient expenses of percutaneous coronary intervention (PCI) and factors in the department of cardiology of a hospital, in order to provide references for setting the upper expenses limit and keeping expenses within a reasonable control Methods The hospitalization expenses data were collected from inpatients having intracoronary stenting operations in a class 3 grade A hospital in Shanghai from 2004-2006. The study made multi-factor analysis on factors possibly affecting the expenses, and built a model to predict the expense per disease, and estimated the upper limit for medical insurance expense control. These figures were used in an expense appraisal for inpatients from January to June in 2007. Results For the expenses of the 1296 PCI inpatients investigated, the largest share, 84.11%, comes from operation materials. Factors affecting the expenses, as listed by their influence, were in turn the number of stents used, length of stay, age, the status at admission, and rescues made. The study found that the average hospitalization expenses of inpatients from January to June in 2007 fell below the middle control line, and 85% of them lower than the upper control line. Conclusions To lower the medical expenses for the disease, hospitals need to take measures by using less stents, less days of stay, and less medication. Control lines specified per disease can help manage and control medical treatment quality.