Throughout the past decade, a possible role of eosinophils in blood coagulation and thrombosis has been suggested. We conducted a Pubmed (MEDLINE) search of case and series referring to any kind of thrombotic events described in three conditions characterised by persistent blood eosinophilia, i.e. the hypereosinophilic syndrome (HES), the Churg Strauss syndrome (CSS), and parasitic infestations from 1966 to date. One hundred and ninety-two articles were found regarding thrombotic events in HES and CSS, and 209 cases of thrombosis were extracted. One hundred and seventy- seven articles dealing with parasitic diseases and thrombosis were found, but only 15 manuscripts reporting thrombosis of unknown origin in 22 patients were selected. In HES, arterial thromboses were more frequent than in CSS (p=0.006), representing almost half of the cases (45%), while venous and mixed artero-venous thrombosis were respectively 28% and 27%. In contrast, in CSS there was a predominance of venous thrombosis (56%, p=0.006), with arterial thrombosis representing 38% of total thrombotic events, and mixed thrombosis being the least frequent (4%). The higher incidence of arterial thrombosis in HES patients can be explained by the common cardiac involvement (64% of patients). In the 22 patients with parasitoses and thrombosis, 15 had arterial thrombosis (68%) and 7 had venous thrombosis (32 %). Literature analysis shows that there are numerous reports of thrombotic events in patients with eosinophil-related disorders supporting a role for eosinophils in thrombosis. This observation raises the problem of prevention and treatment of thromboembolism particularly in HES and CSS patients.