Blood services worldwide have observed a decline in the demand for red blood cells (RBC). Despite this general decline, the demand profile has changed significantly with the demand for O D negative RBCs being maintained; whereas B D positive and AB D positive RBC demand has been reduced. In 2015, the blood type O D negative was seen in 6·3% of the combined first time donors among the five American Blood Centres involved in this study and 7·4% of first time Australian donors in 2014/2015, whereas O D negative distributions accounted for 10·5% of all red cell units issued by the American centres and 13·9% by the Australian centres. Inventory can therefore be of sufficient overall quantity but may not be adequate for the demand for units with specific blood types. Recruitment of new donors may need to become more targeted and/or financial or inventory control measures could also be required to ensure inventory matches demand. Blood Services will need to consider the available options in order to ensure that sufficiency of supply is secure and the donor panel is optimised to meet the new demand paradigm.