Dermatoglyphic asymmetry of fingertip ridge counts is more frequent in schizophrenia patients than normal controls, and may reflect disruptions in fetal development during Weeks 14–22 when fingerprints develop. However, there are no data in humans linking specific adverse events at specific times to dermatoglyphic asymmetries. Our objective was to determine whether prenatal exposure to a natural disaster (1998 Quebec ice storm) during Weeks 14–22 would result in increased dermatoglyphic asymmetry in children, and to determine the roles of maternal objective stress exposure, subjective stress reaction, and postdisaster cortisol. Ridge counts for homologous fingers were scored for 77 children (20 target exposed [Weeks 14–22] and 57 nontarget exposed [exposed during other gestation weeks]). Children in the target group had more than 0.50 SD greater asymmetry than the nontarget group. Within the target group, children whose mothers had high subjective ice storm stress had significantly greater asymmetry than those with lower stress mothers, and maternal postdisaster cortisol had a significant negative correlation with the children's dermatoglyphic asymmetry (r = −.56). Prenatal maternal stress during the period of fingerprint development results in greater dermatoglyphic asymmetry in their children, especially in the face of greater maternal distress.