Methods for making hemoglobin based blood substitute preparations and hemoglobin based blood substitute preparations. The methods involve preparing a low purity erythrocyte protein fraction comprising hemoglobin protein and endogenous non-hemoglobin protein complement, and chemically modifying the proteins in the protein fraction to form a cross-linked hemoglobin containing blood substitute preparation. The low purity erythrocyte protein preparation can contain from at least about 0.2% (mole/mole) up to about 20% (mole/mole) endogenous non-hemoglobin protein complement. At least about 90% (mole/mole) of the hemoglobin proteins can be cross-linked, so that the average molecular mass of cross-linked proteins comprising hemoglobin protein molecules in the preparation is at least about 300 kDa. The preparations can be used to prepare finished blood substitute formulations for in-vivo and ex-vivo use.