Agglomerates suspended in a polymer fluid have been known to disperse in a flow through two mechanisms-rupture and erosion. Using silica agglomerates, it is shown here that a third mechanism can occur, i.e., detachment of fragments due to agglomerate collision. This mechanism requires a much lower overall stress than erosion (and rupture, which occurs at even larger stresses than erosion). The fragment concentration produced by collision at a given time is proportional to the square of the applied shear rate.