As technology advances, diagnostic tests continue to improve, and each year, we are presented with new alternatives to the standard procedures. Given the plethora of diagnostic alternatives, diagnostic tests must be evaluated to determine their place in the diagnostic armamentarium. Criteria include sensitivity and specificity, positive and negative predictive values, likelihood ratios for positive and negative tests, and receiver operating characteristic curves. The prevalence of disease influences the diagnostic utility of tests, particularly when diseases are rare or very frequent.