Medical personnel require many evidence-based medical equations and decision trees for their daily medical practice, medical education and research. Among the hundreds of medical equations, the essential or frequently used equations are not revealed yet. We tried to reveal the most frequently used medical equations and decision trees.

A Korean version of medical equation tool was implemented on the Intranet, which provides 288 medical equations and decision trees. One year after implementation of the system, the log file was analyzed for the use status.

Of the 288 equations and decision trees, 170 items were visited more than once. The creatinine estimation equation was most frequently used (545 times, 18.7%). Body mass index, Apache II score, diabetes screening decision tree, and unit conversion were followed.

We found the frequently used medical equations and decision trees in practice by analyzing the server log file. The list would be a reference for incorporation of selected equations into a computerized prescriber-order entry system.