In cell biology, bulk flow is the process by which proteins with a sorting signal^{[definition needed]} travel to and from different cellular compartments. In other words, bulk transport is a type of transport which involves the transport of large amount of substance like lipid droplets and solid food particles across plasma membrane by utilising energy. Special processes are involved in the transport of such large quantities of materials, which include endocytosis and exocytosis.

It is thought that cargo travels through the Golgi cisternae (from cis- to trans- Golgi) via bulk flow.^{[citation needed]}