Objective: to investigate the effectiveness of the Micro Expression Training Tool (METT) and the Subtle Expression Training Tool (SETT) to help improve the non-verbal communication skills of medical students. Methods: In a randomized controlled trial, all participants were randomly allocated to either a training (n = 41) or control group (n = 41) and were pre-tested before education with METT and SETT at baseline. Then, training students took second tests after a 1-h class about interpreting micro and subtle expressions and control students took the second tests without the class. Results: METT pre-test scores were positively related with female gender, agreeableness, whereas SETT pre-test scores were negatively related with age and positively related with female gender. Mean METT score increases of 29.3% and mean SETT score increases of 36.2% were observed after training, whereas the control group achieved only a mean METT score increase of 11.0% at second testing. Increases in both test scores in the training group were significantly higher than in the control group. Conclusion: METT and SETT are effective, simple tools for improving the micro-and subtle-expression reading skills of medical students. Practice implications: METT and SETT can be effective for improving the non-verbal communication skills of medical students. (C) 2016 Elsevier Ireland Ltd. All rights reserved.