According to the etiological factors the various possibilities of genetic counselling in holoprosencephaly are discussed. In each type of holoprosencephaly a chromosomal analysis is indispensable. Prenatal chromosomal examination of subsequent pregnancies is indicated when dealing with a chromosomal aberration. Fetoscopy is useful under certain conditions. In addition, because of possibly associated neural tube defects, alpha 1-fetoprotein should be determined.