Epithelial ovarian cancer is an aggressive disease with a five-year survival rate of just 45% in the UK. The understanding of steroid hormone metabolism in epithelial ovarian cancer remains elusive. Steroid metabolites have not been fully characterised using mass spectrometry for benign and malignant ovarian masses. I interrogated existing ovarian cancer genomic data to find changes in gene expression for steroidogenic enzymes and receptors and developed a biological study, using mass spectrometry for steroid analysis. I characterised steroid metabolism in epithelial ovarian cancer cell lines and fresh human ovarian tumours (benign, borderline and malignant). I demonstrated a time-course for androgen metabolism in Type 1 and 2 epithelial ovarian cancers cells and replicated this in ex vivo human ovarian tumours, observing several metabolic fluctuations in the newly synthesised steroid products. Unexpectedly, both the cell lines and tumours consistently showed downstream metabolism towards weaker androgens. I then conducted a multi-centre prospective study investigating urinary steroid profiles in healthy women and women with benign and malignant ovarian tumours. In patients with Type 1 ovarian cancers, I identified five urinary steroid metabolites that differentiate them from Type 2 ovarian cancers, benign ovarian tumours, and healthy ovary. Surprisingly, these metabolites are derived in early classical steroidogenesis. Of interest, there were incremental increases in these five steroid metabolites with advancement from healthy ovary to benign mucinous tumour, to borderline mucinous ovarian tumour and to mucinous ovarian cancer. In summary, I show that urinary steroid profiling can be utilised as a diagnostic tool for Type 1 ovarian cancers and provide evidence that steroid metabolism may be involved in the aetiology of mucinous ovarian cancer.