Several photodynamic methods for virus inactivation in red blood cell (RBC) suspensions have resulted in unwanted hemolysis during extended 1–6°C storage. To explore the possibility that hemolysis may be mediated by a membrane-bound dye, a molecule similar in structure to yet different in light absorption properties from the photosensitizer was used as an inhibitor for RBC membrane binding in virus photoinactivation and photohemolysis studies. The addition of 500 μM quinacrine to oxygenated RBC before treatment with 3.6 μM dimethylmethylene blue (DMMB) and 219 mJ/cm² red light resulted in an increased extracellular concentration of the sensitizer, increased extracelluar viral inactivation kinetics, and decreased hemolysis during 1–6°C storage without alteration of quinacrine absorption properties. These results collectively suggest that despite its recognized affinity for viral nucleic acid, DMMB also binds to RBC membranes and that the bound dye is, in part, responsible for photoinduced hemolysis.