Recent studies have shown that a variety of proteins participate with clathrin and clathrin adaptors in receptor-mediated endocytosis. The genes encoding some of these proteins are targets of chromosomal rearrangements in human haematopoietic malignancies. In addition, abnormal expression or mutation of some endocytosis proteins has been reported in human cancers. This article discusses these observations and elaborates the potential mechanisms by which the abnormal expression of endocytosis proteins might participate in the biology of cancer.