It is allegedly known that the thermal stability of the Mint Lift® (the Mint Lift® 17 and the Mint Lift® Fine; HansBiomed Co., Ltd., Seoul, Korea) over time might be lower as compared with thread-lifts processed through ultrasonic molding technology, such as the MEDI ROPE (WSM 19-03; CNG Co., Ltd., Gyeonggi, Korea), because the Mint Lift® undergoes a thermal treatment during the manufacturing process. We conducted this accelerated aging test to compare the thermal stability over time between the Mint Lift® and the MEDI ROPE. Thus, we measured the degrees of strength of the MEDI ROPE, the Mint Lift® 17, and the Mint Lift® Fine at 0, 2, 3, 4, 5, 7, 8, 9, 10, 11, 14, and 17 weeks. Between 0 and 14 weeks, the Mint Lift® 17 and the Mint Lift® Fine had significantly higher degrees of strength as compared with the MEDI ROPE (p < 0.05). At 0, 5, and 10 weeks, the Mint Lift® 17 and the Mint Lift® Fine showed no notable differences in microscopic findings as compared with the MEDI ROPE. At 20 weeks, however, the integrities of the Mint Lift® 17 and the Mint Lift® Fine were better preserved as compared with the MEDI ROPE. In conclusion, our results indicate that the Mint Lift® 17 and the Mint Lift® Fine might be less vulnerable to degradation over time as compared with the MEDI ROPE under thermal conditions.