The literature shows an increase in endothelin-1 with increased levels of erythrocytes. There are also indications that inflammation and elevated endothelin-1 levels interact with erythropoiesis. In this study, the association of erythrocytes and endothelin-1 in women of different ethnicities was investigated. Blood pressure, vascular resistance, and C-reactive protein (P = 0.09) were significantly higher in the African women (n = 102) compared to the Caucasian women (n = 115), while arterial compliance was significantly lower in the African women with no significant differences for endothelin-1. In single, partial, and multiple regression analyses, there was a significant positive correlation between the red blood cell count and log endothelin-1 in the Caucasians while in the Africans there was a weak negative correlation. This is an indication that endothelin-1 might interfere with erythrocyte production in Africans with higher levels of inflammation.