Basic flow properties of asphalt are reviewed. Newtonian and non-Newtonian flow, thixotropy, elasticity, and temperature susceptibility of asphalts are discussed. Microviscometer measurements on paving and industrial asphalts and on synthetic asphalts compounded from asphalt fractions show that asphalt viscosity is primarily dependent on asphaltene content, while chemical composition of the asphaltenes is an important factor. Thixotropy is related to the state of dispersion of the asphaltenes and is strongly influenced by the viscosity of the system. Non-Newtonian character is related principally to the paraffinicity of the asphaltenes. The temperature susceptibility of asphalts is governed to a first approximation by the temperature susceptibility of the malthenes. In the temperature range from 115 F to 180 F, asphalts are more highly thixotropic than at 77 F.