Small cell carcinoma of the ovary is a rare tumour that typically affects young women (mean age of 24 years). In two-thirds of cases it courses with hypercalcaemia and has a very reserved prognosis. Due to its rarity, optimal treatment is not consensual, but most 5-year survivors were submitted to a combination of surgery, adjuvant chemo and radiotherapy. The authors report a case of a 13 year old girl who presented at the emergency room with nausea, vomiting and asthenia. The sole relevant finding on physical examination was a 10 cm nodular formation in the left iliac quadrant of the abdomen. Blood analysis showed hypercalcemia (16.5 mg/dl). Abdominal ultrasound revealed a heterogeneous mass measuring 11x10x7 cm situated in the left pelvic quadrant. Medical therapy was successful in controlling calcium values. An exploratory laparotomy and left ooforectomy were performed. After careful differential diagnosis, histological results revealed a small cell ovarian carcinoma of the hypercalcemic type that was classified as T1aNxM0. The patient was submitted to adjuvant chemotherapy and radiotherapy. Pre- and post-chemotherapy CT-scans were normal. Seventeen months after the diagnosis she is disease free.