To address the role of proficiency testing in the medical usefulness of laboratory tests, nine steps involved in the generation and application of a laboratory test result are identified and discussed: test ordering, patient preparation, specimen, sample, analysis, result, reporting, recognition, and action. Clinical uses of test results are enumerated. Good clinical skills are necessary for optimal test efficiency. Clinicians should improve their selection of tests, pay attention to proper patient preparation, and refine the process of interpretation of test results using disease-based reference ranges and more formal analysis of predictive value. By better definition of the clinical uses of laboratory tests, appropriate attention can be directed to steps in the laboratory domain such as medically relevant goals for accuracy and precision. With clearer understanding of the testing process, proficiency testing for monitoring laboratory performance can be more fully utilized. Audit models should be developed that include assessment of the outcome of the laboratory testing process.