Recent advances have led to an increased understanding of the Ca²⁺-signalling pathway leading to exocytosis in bovine adrenal chromaffin cells. Video-imaging studies have allowed the temporal and spatial aspects of the Ca²⁺ signal to be investigated in detail. Ca²⁺ entry at the plasma membrane appears to be crucial for the activation of exocytosis. Ca²⁺ can enter through the nicotinic channel or characterised voltage-activated channels, or through other poorly defined pathways due to a variety of agonists. Emptying of internal Ca²⁺ stores is sufficient to activate a Ca²⁺ entry pathway. The elevation of cytosolic Ca²⁺ concentration leads to a reorganisation of the cortical actin network and to the triggering of exocytosis. Studies on permeabilised chromaffin cells have resulted in the identification of some of the proteins that control Ca²⁺-dependent exocytosis. These include the peripheral plasma membrane protein annexin II and the cytosolic proteins, protein kinase C and 14-3-3 proteins (Exol).