The current study was performed to obtain insight into the retention of combat lifesaving (CLS) skills after initial training and to compare a more individualized-style training with a more classroom-style training. We measured performance at 0 month, 2 months, and 6 months after initial training in 40 CLSers (17 individualized, 23 classroom). Each test consisted of two 20-minute scenarios with a medical mannequin to simulate combat injuries. An instructor scored the actions, which were divided into critical and non-critical by medical experts. We also measured the speed of performing the protocol and perceived mental effort and anxiety. There were no differences between the groups in critical actions. The full sample made on average almost six critical errors per scenario at 6 months. However, on non-critical actions, the individualized group scored better at 0 month. The individualized group also performed the protocol faster at each test. The classroom group reported an increase in mental effort and anxiety at subsequent tests, while the individualized group did not. Based on the high number of critical errors at 6 months, and on the drop-off in performance at 2 months, we advise that extra refresher training is organized within 2 months after initial training to improve retention further down the line.