Background: This study investigates the outcomes of implementing Six Sigma concept to manage the total waiting time and room turnover time in the operation theater. Methods: Samples were obtained by recording the time of six major-operation activities in one medical centers located at northern Taiwan. The waiting time was divided into three groups (<120 minutes, 121-240 minutes, >240 minutes). Totally, 1,246 patients were collected as the first group (pre-study) while as another 1,266 patients after the improvement of process in the fifth month were collected as the second group (post-study). Analysis was made with descriptive statistics and to compare the differences between the pre- and post-processes. Results: The reduction of waiting time for each study group were 0.54, 4.23, 7.82 minutes respectively (p<0.05); average surgery turnover time significantly decreased for each group also. The quality indicator of Six Sigma were changed from 3.35δto 3.46δ. This confirmed that the intervention of the Six Sigma concept in patient-processing management can minimize the variations in the surgical processes and stabilize the process. Conclusions: The contribution of this study lies in providing administration references for peer general hospitals, surgery departments and administrators in OR with a standard operation procedure to decrease total waiting time for surgical patients as well as to effectively shorten the waiting time for the next-in-line patient.