Several annexins have been implicated in the pathogenesis of benign and malignant neoplasms of different origins. In some tumours a suppressive action of annexins has been shown, whereas studies of other tumours indicate an involvement of annexins in tumour progression. In the light of the expression of annexins at distinct episodes of fetal development these observations point towards a functional role of annexins in cellular development and differentiation. This view is supported by data that link certain annexins to distinct pathways of signal transduction. Auto-antibodies against several annexins have been detected in patients with autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis and inflammatory bowel disease. Until now it is unclear whether their presence reflects a relevant pathogenetic mechanism or merely represents an unspecific expression of a raised autoimmunity in these patients.