This research examined the association between the domestic built environment in a Palestinian refugee camp in Beirut, Lebanon, and the presence of illness among household members. Data on the domestic built environment, socio-demographics and health were collected in 860 households. The association between the presence of illness among household members and three environmental indices, namely infrastructure and services, housing conditions, and crowding was evaluated. These indices were based on a number of items that reflected the existing problems in the domestic built environment. The main finding was the positive association between poor housing conditions and the presence of illness among household members. Households with 8 – 15 housing problems were twice more likely to report the presence of illness than those with less than four housing problems (OR¼2.08, 95% CI¼1.40 – 3.11). This research contributes to the understanding of the influence of the built environment on the health of a refugee population.