The present study was conducted in Wistar rat fetuses to investigate the growth retardation induced by maternal fasting and/or massive doses of ergocalciferol during the third trimester of pregnancy. Growth indices examined in 21-d fetuses were body weight and ossification of sacrococcygeal vertebrae, supraoccipital bone, sternebrae and proximal phalanges in the forepaw stained by alizarin red S. Growth retardation was expressed in hours by comparison with the normal standard development, or in sigma by calculating the relative difference from the control, utilizing the standard variance in normal fetuses. Degrees of growth retardation expressed in the common scales were different among the indices and between fasting and massive doses of ergocalciferol; body weight and ossification of sacrococcygeal vertebrae were most severely retarded by fasting and least by ergocalciferol. Ossification of sternebrae was moderately retarded by fasting and by ergocalciferol, and ossification of supraoccipital bone was moderately retarded by fasting but not by ergocalciferol. Ossification of proximal phalanges in the forepaw was least retarded by fasting and most severely retarded by ergocalciferol. The observed retardations were progressions relatable to the duration of fasting. Combined treatments of fasting and ergocalciferol showed more deleterious effects on growth than fasting only or ergocalciferol only and induced face anomalies, "carnival fetuses." These findings show that growth retardations induced by different nutritional disturbances may vary among indices and that comparisons of various indices are important in the analysis of teratological experiments.