Eight cases of materno-fetal listeriosis were discovered at the University Women's Hospital of Basel from May 1977 until June 1980. This represent an incidence of 0,15% of all births. This infectious disease has often a fatal course for the unborn child, therefore it is important to know the clinical manifestations occurring with it. Listeriosis during pregnancy has a typical-two-stage course: During the first phase we see commonly a flu-like illness abating rapidly, about two weeks later fever starts again and premature contractions ensue, but no therapy is successful in controlling the fever and the premature labour. The usual fate for the unborn child is stillbirth or premature delivery with subsequent neonatal death due to prematurity, RDS, sepsis and meningitis. The low fetal and neonatal survival rate can be improved by two relatively simple measures: 1) a high index of suspicion with early diagnosis, 2) an early treatment with ampicillin either in the antepartal or neonatal stage. We review the epidemiology, the bacteriology, the serology and the histo-pathology of this relatively rare but important disease during pregnancy.