This study evaluates appointment systems used in hospitals by incorporating appointment rules and patient characteristics. Using an experiment unit at an internal medicine department of a large outpatient ward in Nagoya university hospital, a number of prevailing assumptions were relaxed, and twenty-five appointment systems were developed combining five appointment rules with five patient sequences. These appointment systems were evaluated under two different environments namely no-show and patient punctuality, with each of the two-levels totaling one-hundred different environments. A best appointment system is capable of identifying the problems in terms of both patient waiting time and doctor idle time.