The hypothesis was tested that prenatal alcohol exposure disrupts developmental homeostasis, as reflected in increased dermatoglyphic fluctuating asymmetry. Twenty-two patients with fetal alcohol syndrome (FAS) and 9 with fetal alcohol effect (FAE) were matched for sex with 31 controls. On each patient, the right a-b dermal ridge count was subtracted from the left to obtain the asymmetry value. Group differences were tested by analysis of variance (ANOVA), and paired two-tailed t tests. Mean asymmetry increased from control (1.94) through FAE (2.78) to the FAS (4.00) group. Group differences were significant by ANOVA (p = 0.0066); only the FAS and control group differed by t test (p = 0.0025). The results support the hypothesis of increased decanalization of prenatal development in the presence of alcohol.