Consanguineous marriage that defines as a union between biologically related persons has a variety of known deleterious correlations with factors that affect public health within human populations. To investigate the association between the mean of inbreeding coefficient (α) and incidence of leukemia, the present ecological study on 68 countries was carried out. Statistical analysis showed that the age-standardized incidence rate of leukemia positively correlated with log10GNI per capita (r=0.699, df=66, P<0.001) and negatively correlated with log10α (r=-0.609, df=66, P<0.001). Controlling log10GNI per capita, a significant negative correlation between log10α and the age-standardized incidence rate of leukemia was observed (r=-0.392, df=65, P=0.001). The countries were stratified according to their annual GNI per capita, low and high-income countries with GNI per capita less than and more than 10,000$, respectively. Statistical analysis showed that in high-income countries, after controlling for log10GNI per capita, the correlation between the age-standardized incidence rate of leukemia and log10α was still significant (r=-0.600, df=36, P<0.001). It should be noted that there was no significant association between the age-standardized mortality rate due to leukemia and log10α (P>0.05). The present finding indicates that the rate of leukemia, age-standardized for incidence, is lower in countries with a high prevalence of consanguineous marriages.