Mucinous carcinoma of the ovary remains one of the least well-understood and explored gynaecological cancers. Diagnosis can be challenging, and specialist pathological input and thorough tumour sampling are essential. The prognosis varies significantly according to grade, stage and subtype of expansile or infiltrative pattern of invasion. Treatment largely follows that of other ovarian cancer histological subtypes, but there is a lack of data specific to mucinous carcinomas to support this and there is uncertainty regarding the benefit of adjuvant chemotherapy in early-stage disease. In advanced disease, mucinous carcinomas are relatively resistant to chemotherapy and whether gastro-intestinal regimens are better than standard platinum/taxane regimens is also unknown. Recently, understanding of molecular biology has improved to highlight the importance of KRAS mutations, TP53 mutations and ERBB2 amplification and to demonstrate the stepwise progression from mucinous ovarian cystadenoma to borderline mucinous ovarian tumour to mucinous ovarian carcinoma. Further research is required in order to develop novel molecular and targeted therapies, which hopefully will help improve outcomes in this disease. The genomic and methylomic landscapes, potential targets and therapies, including HER2 targeted agents, are described. International collaboration is essential in this rare subtype and shared clinical databases, scientific initiatives and clinical trials are required to improve understanding and outcome.