During our investigations on helminthofauna in roe deer (Capreolus capreolus) and red deer (Cervus elaphus) in France (1985-1998) we isolated nematodes not only of the genus Haemonchus Cobb, 1898 but also of the genus Ashworthius Le Roux 1930, both of which belong to the same subfamily of Haemonchinae. The prevalence of Ashworthius was 22% (65/294) in roe deer and 40% (10/25) in red deer. H. contortus was not found in red deer, whereas its prevalence was only 3% (9/294) in roe deer. These data contrast with those observed in other European countries. The presence of A. sidemi in red and roe deers in France suggests a case of parasitism imported via sika deer. A hypothesis of their spread is proposed.