The percentage of DVT associated with treatment with thalidomide and chemotherapy including dexamethasone varies according to the series (4–28%), we found an overall incidence of 12% (6/50) of DVT in patients receiving thalidomide but when patients developed Acquired activated protein C resistance (ACP-R), the DVT incidence increases (66%). The gene discussed is PROC; the disease is deep vein thrombosis.