Although there is an increased cardiovascular risk in the immediate weeks following bereavement, the mechanism is not well understood. The aim of this study was to determine whether inflammatory and thrombotic changes were present in acute bereavement. Eighty bereaved spouses or parents were prospectively studied within 2 weeks of bereavement (acute) and at 6 months, and compared to 80 non-bereaved participants. Haemostatic measures were obtained between 8 a.m. and 11 a.m. and processed within 1 h. Compared to non-bereaved participants, those acutely bereaved had a higher neutrophil count (4.34 ± 0.19 vs 3.79 ± 0.15, p = <0.001), von Willebrand factor antigen (132.33 ± 3.6 vs 119.95 ± 3.29, p = 0.02), Factor VIII (1.43 ± 0.06 vs 1.25 ± 0.04, p = 0.02) and platelet/granulocyte aggregates (median 383.0 vs 343.5, p = 0.02). Levels of neutrophils, monocytes, eosinophils, platelet count, platelet/monocyte granulocytes and von Willebrand factor were lower in bereaved at 6 months compared to acutely (all p < 0.05). Acute bereavement is associated with inflammatory and prothrombotic changes that may contribute to the increased cardiovascular risk with bereavement and provide clues for future preventative strategies.