The UN estimates that the global population will reach 10.9 billion by the end of the century. Much of this growth will come from Muslim-majority countries — most of which are completely unprepared for such an expansion in their populations. One key issue identified by the UN is emerging health inequalities that will be exacerbated by poor infrastructure, poverty and stagnant economies. In order to fully understand this challenge, it is useful to examine the social determinants of health in terms of income differentials, social systems and political choices, and different disease prevalence across ethnic groups. The main factors cited are often variances in nutrition, education, employment and living environment, but the concept can become rather nebulous when drawn too widely or where population groups with substantial differences are compared. The existing research tends to show predictable between-country variations due to socioeconomic status and gender relating to differences in morbidity and mortality. However, much less is known about the cross-national variability of health outcomes and health inequalities tied to ethnicity, race or migration status. In general, we know that marginalized minority groups often experience earlier mortality and worse overall health relative to majority populations. This starts to point to some of the complexities. In some instances, the Muslim population is made up largely of migrants who may suffer varying degrees of social exclusion, prejudice and problems accessing healthcare. The COVID-19 pandemic has reinforced long-known links between poor health and low income, but also in many countries points to the ways in which low income is related to ethnicity. In turn, in many countries, certain ethnic groups are also often Muslim-majority. In Europe, this partially follows the patterns of colonial control, so most of France’s North African communities are Muslim, while in the UK the same is true for those from South Asia. However, other communities are the result of migration for work, such as the Turkish community in Germany, or the result of refugee crises. Globally, the Muslim population can be split between those who are minorities in their particular state and those who live in Muslim-majority countries. In the first instance, in addition to their religious identity (and often particular ethnic backgrounds), the issues revolve around the degree of social exclusion in that state. In Muslim-majority states, the issues can often be linked to questions of governance as much as the actions of the Muslim community itself. Thus, in contrast to Pakistan, Bangladesh is often praised for sustained efforts to improve population health, including access for women. Finally, Islam’s widespread prohibition on alcohol usage helps to remove a major source of ill health in other social or religious groups. Equally important, Islamic teachings on charity and income equality can, potentially, have a powerful role in Muslim-majority countries, but are harder to apply where the Muslim community is a minority. Also, as a community, the provision of healthcare is an important feature reflecting the importance of social interaction within the faith. Muslim-majority countries are mostly in an arc across northern Africa and the Middle East to Bangladesh. For the most part, these are relatively poor countries, apart from the low-population hydrocarbon states in the Gulf region. Within this group, there are health successes despite low levels of income, in particular Bangladesh, which is often cited as a success story. Equally, there is no systemic difference between Muslim-majority countries and their immediate neighbors in regions such as sub-Saharan Africa. What is left is actually good or bad policy choices, linked to better or worse governance. Islam offers economic tools for poverty alleviation. The key challenge in the Muslim world remains — it is poverty that drives many of the health problems and limits the ability of the population to mitigate and adapt to the rapidly emerging health problems associated with climate change.