Volumes of nuclei of nervous cells of cortex (C) and caudate nucleus (CN) in brains of fetuses of mothers maintained on methionine--low diet (MLD) or on standard diet (STD) for 2 months before conception and throughout pregnancy were compared acc. to Hintzsche. In both brain areas the class ranges of C and CN nuclei of nervous cells were shifted to the left in fetuses from mothers maintained on MLD and this distribution difference was highly statistically significant. This shows that the nuclei of nervous cells of fetuses of mothers maintained on MLD were retarded in growth.