Ovarian cancer is the most common fatal gynaecological malignancy. Tumours of the stroma and/or sex cords represent approximately 8% of ovarian tumours and develop from the connective tissue of the ovaries. Because these cells participate in ovarian hormonal function, most of the sex-cord stromal tumours are able to secrete hormones, which explains the hormonal dysfunctions associated with these cancers. By far the most common of these tumours are the granulosa cell tumours (GCT). Adult GCT are characterized by a mutation in the FOXL2 gene (C134W), which is absent in the less common juvenile form (which represent 5% of GCT). GCT exhibit many morphological, biochemical and hormonal features of proliferating normal pre-ovulatory granulosa cells, including both estrogen and inhibin biosynthesis; inhibin has proven to be a useful tumour marker. GCT are characterized by an indolent course, and a high rate of late recurrence. Most GCT are stage 1 and are cured surgically, however, ~80% of patients with aggressive or recurrent tumours die from their disease. Chemotherapy and hormonal therapy have proven to be of limited efficacy. In order to address the key questions of pathogenesis and targeted therapeutics, our strategy has been to examine the role of: 1) nuclear receptors in the pathogenesis of GCT (in particular ER and PPAR); 2) constitutive NF-B activity in the human GCT-derived cell lines COV434 and KGN; and 3) microarray analysis of adult GCT segregated by stage. The above studies have identified several potential, novel, GCT-specific therapeutic strategies which are the subject of ongoing investigations. As with other uncommon tumour types, insights from research on GCT may be prismatic, i.e. by clarifying mechanisms of normal ovarian function, and providing insights into other dysfunctions of the ovary such as other sex cord-stromal tumours, premature ovarian failure, polycystic ovarian syndrome and infertility.