The utility of molecular diagnostics in clinical practice has been steadily increasing and is expected to continue to do so as the applications of genomic medicine increase. The goal of this article was to describe the roles and responsibilities of genetic counselors who work in the customer service area of molecular diagnostics laboratories. In this role, genetic counselors provide recommendations to clinicians on issues that are specific to DNA-based testing. This article will address some issues that are specifically relevant to disease genetic tests. Many molecular diagnostic laboratories employ genetic counselors, who have extensive training in how to communicate genetic information, to provide information in the preanalytic, analytic, and postanalytic stages of testing. To maximize the quality of the service, it is important to establish an understanding of what can be expected of both the practitioner and the laboratory genetic counselor. Although some complications in the laboratory cannot be anticipated, discussing the case with the laboratory genetic counselors beforehand may avert certain problems. This article discusses real cases from laboratory genetic counselors to illustrate issues that arise due to technical difficulties and the inherent limitations of molecular testing. The summary describes practical ways in which clinicians and laboratory personnel can work together to either avoid or, when unavoidable, better manage problems and delays. The responsibilities of genetic counselors working in molecular diagnostics are discussed.