Agriculture is an important source of income for the Islamic State in Syria and Iraq (ISIS), which currently rules over large parts of the breadbaskets of the two countries. It has received limited attention compared to other sources of ISIS revenues such as oil, looting, ransom, foreign donations and various forms of taxation. We estimate winter crops production of wheat and barley in ISIS-controlled areas in both Syria and Iraq for the years 2014–2015 and irrigated summer crops production (cotton) in Northeast Syria. We show that remote sensing can give a credible estimation of agricultural production in the absence of statistics. With evidence from MODIS Aqua and Terra Satellites as well as Landsat imagery, we find that agricultural production in ISIS-controlled Syrian and Iraqi zones has been sustained in 2014 and 2015, despite the detrimental impact of conflict. After a drought in 2014 production was able to capitalize on improved rainfalls in 2015. First indications show that the winter grain harvest of 2016 in Iraqi territories of ISIS was significantly above pre-conflict mean and below pre-conflict mean in its Syrian territories. We also show how water flows along the Euphrates have impacted production. We estimate the revenue that ISIS can derive from wheat and barley production and the likely magnitude of an exportable surplus. Agricultural production gives the group a degree of resilience, although its economy is not sustainable in the longer run and could be affected by military collapse. Taxation of recurrent income streams such as agriculture will become more important for ISIS as its extractive sources of revenues show signs of dwindling. Beside non-grain food imports, agricultural production is crucial for its political legitimacy by ensuring food provision to the broader population. Food security considerations would require a high priority in any post-ISIS reconstruction effort and would need to include the rehabilitation of supply chains for agricultural inputs such as quality seeds and fertilizers.