Cat-scratch disease (CSD) was first described by Debré in 1950, yet the causative bacterial agent of CSD remained obscure until 1992, when Bartonella (formerly Rochalimaea) henselae was implicated in CSD by serological and microbiological studies. B. henselae had initially been linked to bacillary angiomatosis (BA), a vascular proliferative disease most commonly associated with long-standing human immunodeficiency virus (HIV) infection or other significant immunosuppression. B. henselae has also been associated with bacillary peliosis, relapsing bacteraemia and endocarditis in humans. Cats are healthy carriers of B. henselae, and can be bacteraemic for months or years. It has recently been demonstrated that B. henselae can be transmitted from cat to cat by the cat flea, but not by direct contact between animals. The author discusses the present state of knowledge on the aetiology, clinical features and epidemiological characteristics of cat-scratch disease and bacillary angiomatosis.