Heat transfer to a Bingham plastic in laminar tube flow with transient internal heat generation is investigated. Numerical results are obtained for the temperature response of the fluid and tube wall when subjected to step and sinusoidal variations in the heat generation rate. A resonance phenomenon is observed for the frequency response, and the Bingham plastic responds faster than a Newtonian fluid following a step in the internal heat generation. Experiments with both Newtonian fluids and slurries of aluminum in sulfuric acid show agreement with the theoretical predictions. However the effects of combined free and forced convection, as well as nonuniform dispersion of solids in a slurry, result in an axially asymmetric temperature distribution. Heat exchangers whose design is influenced by these gravity dependent phenomena include the homogeneous nuclear reactor and chemical reactors.