A common problem in the manufacture of liquid protein therapeutics is the tendency for aggregation and particle formation on extended storage. One aspect of processing that might contribute to particle formation is pumping. In the present study, we demonstrate that lobe pumps can promote aggregation in albumin preparations. This is accentuated where the clearance between the pump housing and lobes is increased. Under these conditions, the pump efficiency decreases, resulting in increased exposure of the protein to the pump environment. Depending on the inherent physicochemical stability of the protein, this can lead to aggregate formation, which can influence the long-term stability characteristics of the product.