Mnemonic training can improve episodic memory function, the most aging-sensitive functional domain in older adults. However, it remains unclear whether memory training gains can be maintained over time. In this meta-analysis, we aimed to investigate the long-term effects (pretest to follow-up) of mnemonic training in improving memory among older adults. Eligible studies were randomized controlled trials of mnemonic training with follow-up assessments (ranging from 0.5 to 32 months, median follow-up duration = 4 months) in healthy older adults (aged ≥ 50 years) without known cognitive impairment. Twenty-one studies, with a total of 4,149 participants, were identified. The three-level meta-analyses indicated that the immediate (pre- to post-test) and long-term effect sizes on episodic memory were 0.408 and 0.418 (Hedges'g, ps < .001), respectively. In addition, the results revealed significant immediate effect (g = 0.362, p < .01) and long-term effect (g = 0.227, p < .01) on subjective memory. It is recommended that future studies incorporate more real-world outcomes and multiple follow-ups and boosters to determine training effects on everyday functioning over time. (PsycInfo Database Record (c) 2022 APA, all rights reserved).