Appropriate establishment and maintenance of cell polarity is essential for normal development and homeostasis. The vast majority of human cancers originate from epithelial tissues and tumour cell invasion and metastasis are the major cause of mortality in human cancers. Invading cells demonstrate loss of cell polarity, loss of epithelial cell-cell adhesions and tissue disorganisation. We examine the growing evidence linking loss of apicobasal polarity with tumour progression.