Objectives: Type 1 diabetes mellitus (T1DM) in childhood has impacts on patients' daily lives. The Pediatric Quality of Life Inventory (PedsQL^TM) 3.0 Diabetes Module is a questionnaire of health-related quality of life (HRQOL) specified for T1DM. This study was aimed to assess the reliability and validity of the Korean-translated version of the PedsQL^TM 3.0 Diabetes Module in children and adolescents with T1DM. Methods: One hundred and two patients (aged 8~18 years) with T1DM and their parents, who were outpatients from 5 teaching and university hospitals in Daegu, Korea, participated in this study. Child self-reports and parent-proxy reports of the Korean version of the PedsQL^TM 3.0 Diabetes Module were completed. As a health index, hemoglobin A1c and self-health status were collected. Results: More than 90% of the items were answered and the missing rate was minimized, which supported a good face validity and feasibility. The internal consistency of the PedsQL^TM 3.0 Diabetes Module, Korean version, reached or exceeded Cronbach's alpha values of 0.70 for both child self reports and parent-proxy reports. The test-retest was highly correlated (r=0.82, 0.87) and the intraclass correlation coefficient (ICC) exceeded 0.6 in all sub-scales for child self-reports and mostly for parent-proxy reports. Children's HRQOL for child self-report was correlated with hemoglobin A1c and self-helath status (r=-0.33, 0.32). Conclusions: In summary, this study represented that the Korean version of the PedsQL^TM 3.0 Diabetes Module was feasible, reliable and valid for measuring the specific HRQOL in patients aged 8~18 with T1DM. Furthermore, a larger study to compare the Diabetes Module with the PedsQL Generic Core Scales is needed.