The attachment conditions under which sickle red blood cells (SRBC) adhere to endothelium were to alter both the extent of SRBC interactions with endothelium and the fluid drag forces opposing adhesion. Cytokine stimulated endothelium was used for static and parallel plate adhesion assays at 1.0 and 2.0 dyn/cm2 nominal wall shear stress to obtain adhesion. Initially-adherent SRBC were quantified and then isolated for subsequent removal via micropipette aspiration. Initial SRBC adherence mediated by α4β1:VCAM-1 interactions was greatest under moderate shear flow conditions. The average detachment forces required to remove adherent SRBC from the endothelium were 17.4 ± 5.2, 30.9 ± 10.8, 43.9 ± 13.1 μ dynes for the respective static.