The Korean Association of External Quality Assessment Service provides proficiency test (PT) materials through a logistics company. We investigated the delivery times of PT materials in 2020 and the methods to reduce delivery delay. We also attempted to prolong the proper storage temperature with the addition of ice pack. Methods: The lead times of deliveries from 2020 were calculated. We also checked the duration for which 600 g×6 packs of dry ice or 24×16 cm ice gel packs could maintain the

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... oper temperature. To reduce delivery delay, the delivery day for HbA1c testing material was changed from Monday to Tuesday. To prolong the duration of proper temperature maintenance for cold shipping, an extra 12×17 cm ice gel pack was added. Results: The average delivery time was 23 hours, 5 minutes, and 12 seconds (min-max: 17:9:8-84:31:39). The average delivery delay rate was 2.81% (minmax: 0.23%-11.25%). The delay rate for shipping on Monday was 11.25%; changing the delivery day to Tuesday reduced the delay rate to 1.76%. The addition of a 12×17 cm-sized ice gel pack along with the 24×16 cm gel pack prolonged the duration of proper storage temperature maintenance for cold shipping by 6 hours. Conclusions: Shipping on Tuesday instead of Monday can be an effective option to reduce the delivery delay rate, and the addition of a 12×17 cm ice gel pack can prolong the proper cold shipping temperature.