The use of clinical laboratory testing by primary care optometrists has several legal ramifications. Because laboratory testing is largely controlled by state law, optometrists must comply with the specific statutory provisions that pertain to the ordering of tests. If patients present with ocular signs or symptoms indicative of systemic disease, optometrists should order the appropriate tests or refer the patient to another health care provider so that the appropriate testing can be obtained. In ordering clinical laboratory tests to confirm a presumptive diagnosis, optometrists will be held to a medical standard of care with respect to the interpretation of results, the prompt communication of results to patients, and the reordering of tests that have produced questionable or incorrect findings. Test results, communications with patients, and recalls and referrals should be documented in the record of care.