African immigrants living in the United States are exposed to the stress of changing continents and cultures. Therefore African immigrants are exposed to two types of environmental stress; first, stress related to navigating new social and economic realities; and second, stress due to work, education and a sedentary lifestyle in the United States. To evaluate the effect of these stressors on health, we calculated the allostatic load score in two groups of Africans: childhood immigrants who came to the United States before 18 years of age, and adulthood immigrants who came to the United States at 18 years of age or older. Allostatic load is a measure of the influence of environmental stress on physiological function. It is calculated for each individual by assigning one point for each high risk cardiovascular, inflammatory, and metabolic biomarker present. The higher the allostatic load score, the greater the impact of stress on physiologic dysregulation. As no consensus exists on which biomarkers to include in the calculation of allostatic load score, we used four different published equations to evaluate allostatic load in 213 African immigrants (age: 40±10y,(mean±SD) range 21-64y; BMI: 27.7±4.5 kg/m2; male: 70% (149 of 213); adulthood immigrants: 81% (181 of 213)). By multiple regression, the effect of age, age at immigration, duration of stay in the United States, income, education and exercise on allostatic load score was determined. Overall, childhood immigrants were younger than adulthood immigrants (29±7 vs. 41±9y, P<0.01). However, length of residence in the United States was longer for childhood immigrants than adulthood immigrants (19±8 vs. 12±9y, P<0.01). Regardless of which equation for allostatic load score was used, childhood immigrants had lower allostatic load scores than adulthood immigrants, (P<0.01). Among adulthood immigrants, the age range of immigration was 18 to 61y; within this group, lower age of immigration was associated with lower allostatic load scores (P<0.05). In addition, as length of stay in the United States increased, allostatic load score increased in adulthood immigrants (P<0.01) but not childhood immigrants (P>0.6). For both groups of immigrants, low income, lack of a college education and low levels of exercise did not increase allostatic load score (P>0.3). Overall, the factor which appears to have the greatest impact on the physiologic health of African immigrants is age of immigration. Africans who emigrated as children experience less physiologic stress than their counterparts who emigrated as adults.