Cytological and biochemical investigations were carried out on 60 samples of amniotic fluid obtained from 30 pregnant women with risk for development of fetal central nervous abnormality (FCNA) and 30 pregnant women in whom prenatal diagnosis was indicated for other reasons (control group). Cytological evaluation was done in an interference-polarization Nomarski microscope evaluating the cells in direct preparation and after staining with neutral red. Parallelly with cytological evaluation alpha-1-fetoprotein (AFP) and acetylcholinesterase (AChE) were determined in amniotic fluid. In three cases with open neural tube anomaly characteristic cells with strongly puckered and vacuolized cytoplasmic membranes were found. In these cases the levels of AFP and AChE exceeded the normal range. In two cases of closed abnormalities of the central nervous system diagnosed by ultrasonography no abnormalities were note by cytological and biochemical methods. The study confirmed the usefulness of the cytological examination of amniotic fluid, as a method supplementing biochemical and ultrasonographic investigations as part of prenatal diagnosis.