Mucoepidermoid carcinoma (MEC) is a relatively uncommon carcinoma of variable histology that can involve many tissue types, most commonly major and minor salivary glands and the tracheo-bronchial tree. In a significant number of cases a recurring t(11;19) translocation with an associated novel fusion oncogene (CRTC1-MAML2) is present. This translocation is also found in Warthin's tumour and clear cell hidradenoma of the skin. The CRTC1-MAML2 oncogene acts as a transcription factor on Notch and CREB regulatory pathways, disrupting normal cell-cycle and differentiation, contributing to tumour development. Data suggest that in MEC, the presence of CRTC1-MAML2 may have some prognostic value. An understanding of these mechanisms extends our knowledge of the role of fusion oncogenes in epithelial malignancy. A review of CRTC1-MAML2 in MEC is presented.