Tumour of unknown primary (primum ignotum) is a metastatic disease that generally shows a poor response to treatment and prognosis. Although it exhibits a trend of decreasing incidence, the diagnostic processes are complicated. The available literature shows that 5–30% of metastases involve the ovary, but it remains unclear how often ovarian infiltration is found in tumours of unknown primary. The most common metastatic disease that affects the ovaries are malignant tumours of the gastrointestinal tract, breast, pancreas, and haematological malignancies. Usually, the first step to distinguish between a primary and a secondary tumour of the ovary is an ultrasound examination, where the ovarian metastases have some characteristic features. Here we report our experience with primum ignotum in a patient with simultaneous ovarian and bone marrow involvement.