Development of lipid-based fine particles as potential drug carriers requires detailed investigation of possible effects of these carriers on rheological properties of blood. In this study, we have investigated the influence of dynamic conditions on aggregate formation and stability in dispersions of lipid-based fine particles in whole blood under in vitro conditions. Rheological parameters of two concentrations of liposome dispersion and two concentrations of lipid emulsion in blood were studied by assessing shear stress/shear rate relationships. The magnitude of attractive interactions between aggregates and/or particles, A, and the effective-to-real volume fraction of particles, phi(f)/phi(p) , were estimated for rheological quantification of lipid-based fine particles-blood interactions and aggregate stability. Addition of lipid-based particles induced aggregate formation in blood, which was more pronounced at higher concentrations of lipid-based fine particles. Furthermore, larger and more stable aggregates were formed in liposome dispersions as compared to lipid emulsions in blood.