The Wisconsin Card Sorting Test, Stroop Test, Verbal Fluency (FAS), and Auditory Consonant Trigrams are commonly used measures of prefrontal lobe dysfunction. However, insufficient data are available regarding the specific functions assessed by these tests and the relationship of the tests to each other. These four tests, as well as measures of IQ, memory, attention, and processing speed, were administered to 250 subjects (138 patients and 112 controls). Factor analysis yielded three factors, and a higher order frontal lobe factor, using a dimensional factor analytic methodology. Present findings revealed modest correlations among the prefrontal tests, suggesting that the tests tap somewhat different abilities and are not redundant. Adequate assessment of prefrontal lobe abilities appears to require use of more than one test.