The use of molecular genetic tests for heritable conditions is expected to increase in medical settings, where genetic knowledge is often limited. As part of a project to improve the clarity of genetic test result reports to minimize misunderstandings that could compromise patient care, we sought input about format and content from practicing primary care clinicians. In facilitated workgroup discussions, clinicians from pediatric, obstetrics-gynecology, and family practice provided their perspectives about molecular genetic testing with a focus on the laboratory reporting of test results. Common principles for enhancing the readability and comprehension of test result reports were derived from these discussions. These principles address the presentation of patient-and test-specific information, the test result interpretation, and guidance for future steps. Model test result reports for DNA-based cystic fibrosis testing are presented that were developed based on workgroup discussions, previous studies, and professional guidelines. The format of these model test reports, which are applicable to a variety of molecular genetic tests, should be useful for communicating essential information from the laboratory to health care professionals. Medical test results inform clinical decision making and can influence patient and family attitudes and action. The reporting of molecular genetic tests for heritable conditions by the laboratory issuing the report to the health care provider is complex because interpretation of the test result frequently relies on patient-and family-specific information. Studies have shown that proper interpretation of test results can be compromised by practices in both laboratory and clinical settings by factors that relate to the collection and use of patient-and family-specific information, variation and format of test requisitions and result reports, and the competency of medical staff, especially those lacking specialized knowledge of genetics.