BACKGROUND:There are already several existing studies that show the effectiveness of mindfulness-based approaches in varying types of disorders. Only a few studies, however, have analyzed the effectiveness of this intervention in psychosis, and without finding, up to now, significant differences from the control group. AIMS: The aim of this study is two-fold: to replicate previous studies, and to focus on analyzing the feasibility and effectiveness of applying mindfulness in a group of people with psychosis. METHOD: Eighteen patients with psychosis were randomly assigned to experimental and control groups. The experimental group received eight 1-hour sessions of Mindfulness-Based Cognitive Therapy (MBCT), while the control group was relegated to a waiting list to receive MBCT therapy. RESULTS: The experimental group scored significantly higher than the control group in their ability to respond mindfully to stressful internal events. CONCLUSIONS: Both the usefulness and effectiveness of implementing a mindfulness-based program have been replicated in a controlled manner in patients with psychosis.