MSF has been present in Yemen since 2007. After war broke out in 2015, MSF intervened at a referral hospital in Hajjah, an administrative area at the frontlines of the fighting and host to nearly half of the country’s estimated 2.76 million internally displaced persons (IDPs). In 2016, the hospital treated 3438 war-wounded persons, and as the conflict drags on, both host and IDP communities continue to suffer from shortages of food and clean water and a severe lack of access to quality healthcare. That includes care for the mental health (MH) of affected communities, which appears to have deteriorated. MSF collected and analysed data on all patients who received psychological support from MSF between November, 2016 and February, 2017. Further to this, the study summarises the lessons learned regarding the challenges and impact of MSFs mental health work in this context.