SummarySeveral years ago,Rochalimaea henselaehas emerged as an agent of bacillary angiomatosis, bacillary peliosis and recurrent septicaemia that generally occur in patients infected with human immunodeficiency virus. An aetiologic role in cat scratch disease is also suspected widely on the basis of a serologic survey. Its slow growth and its culture requirement explain that this pathogen, a gram-negative bacterium, could not be isolated until 1990. Moreover, blood and tissue samples request lysis and crushing for recovering by culture. The clinical, histological, microbiological and pathogenic aspects of these in;fcctions are described and discussed.