AIM: To assess the effect of a 4-week mindfulness-based training intervention on improving stress, anxiety, depression and job satisfaction among ward nurses. BACKGROUND: Previous literature showed that mindfulness-based training is useful for helping nurses cope with stress. METHOD: Nurses who have mild to moderate levels of stress, anxiety and depression identified from a teaching hospital were invited to a randomized control trial. The intervention group had a 2-hr Mindfulness-Based Training workshop, followed by 4 weeks of guided self-practice Mindfulness-Based Training website. Both the intervention group (n = 118) and the control group (n = 106) were evaluated pre- and post-intervention, and 8 weeks later (follow-up) using the Depression, Anxiety, and Stress Scale-21, Job Satisfaction Scale and Mindful Attention Awareness Scale. RESULTS: There was a significant effect over time on stress, anxiety, depression and mindfulness level (p < .05). Regarding the difference between the groups and interaction between time and group, there was a significant effect for anxiety (p = .037 p = .008) and job satisfaction (p < .001, p = .40), respectively, with moderate effect size for anxiety reduction (.465) and small for job satisfaction increment (.221). CONCLUSION: Mindfulness-Based Training is effective in improving anxiety and job satisfaction among nurses. CLINICAL IMPLICATIONS FOR NURSING MANAGEMENT: Mindfulness-Based Training can be included as hospital policy to reduce anxiety and increase job satisfaction among nurses.