In order to discover whether laboratories have policies regarding the testing of unaffected children, we surveyed all laboratories registered with Helix, a national net-work of DNA diagnostic laboratories. Of 186 laboratories asked to respond anonymously to a four-page questionnaire, 156 (84%) replied. A screening question removed 51 laboratories that provided no clinical services. Of the remaining 105, 92% said that their requisition forms asked the person's age. Substantial minorities had policies for the testing of minors for late-onset disorders (46%), for carrier status for recessive disorders (33%), or for disorders for which the test offers no medical benefit within 3 years (33%). Most laboratories are responsive to parental requests. For 12 of 13 late-onset disorders, the majority of laboratories that offered testing had had requests to test children. The majority had tested healthy children, <12 years of age, for eight disorders. Approximately 22% had tested children, <12 years of age, for Huntington disease. Majorities had received requests to test healthy children for carrier status for 10 of 15 recessive or X-linked disorders and had tested children, <12 years of age, for 6 of these disorders, including cystic fibrosis, hemophilia A, fragile X syndrome, and Duchenne muscular dystrophy. Approximately 45% of the laboratories occasionally had provided tests directly to consumers. In view of the possibility that the harms of presymptomatic diagnoses of children sometimes may outweigh the benefits, our results suggest a need for consistent laboratory policies designed for the best interests of the child and the family.