In recent years, mindfulness meditation has shown to be a promising approach for alleviating disability and dysfunction associated with a wide range of medical and psychiatric conditions. To date, there have been no controlled clinical studies of mindfulness for problem gambling (beyond case studies) despite the well-established presence of irrational beliefs and cognitive distortions which would suggest that mindfulness interventions would be particularly suitable. In the present study, a group, five-session, mindfulness intervention was integrated into an empirically-effective cognitive-behavioral therapy for problem gamblers. Compared to a wait list control the mindfulness intervention significantly reduced the severity of gambling, gambling urges and psychiatric symptoms at end-of-treatment. At the 3-month follow-up combining the results of both groups the results were maintained. In addition, a significant decrease in the proportion of the sample meeting criteria for pathological gambling was found. Those individuals who reported some mindfulness practice post-treatment showed significantly better clinical outcomes than did those who did not report any mindfulness practice suggesting that mindfulness did play a role in the outcomes observed. Taking into consideration the multiple methodological limitations of this pilot study there is sufficient evidence to further investigate the potential efficacy of mindfulness interventions for problem gambling.