Risk factors for venous thromboembolism in cancer vary between tumours. Leucocytosis, thrombocytosis, tumour histology and vascular compression may drive thrombosis in ovarian cancer. Thrombosis developed in 13.4% of our patients. Higher median leucocyte, neutrophil and monocyte counts were related to thrombosis. Thrombocytosis >350 × 109/L was frequent (63.8%), but not predictive of thrombosis. Identification of prothrombotic biomarkers may help personalise preventive treatments.