This paper is the fourth in a series dealing with encephalopathy due to brain injury and brain disease. The test results indicate that the functioning and efficiency of the patients in both groups follow a similar pattern: full scale IQ's within the normal limits, verbal scores significantly higher than performance ratings, and low intergroup differences for full scale, verbal, and performance scales. The brain-injured patients, on the average, showed more marked discrepancies between the verbal and performance subtests. The functions that are impaired or inefficient are discussed. The author holds that the statistical findings do not fully justify the quantitative interpretation that such rigid constructs as mathematical limits would imply. The effects of an encephalopathic process are serious but an unmeasurable consideration must be given to the impact upon the personality structure of the patient. It is questionable whether any statistical technique exists at present which could factor out this pervasive element satisfactorily.A comparison of the performances of both groups on the Bellevue Intelligence Scale shows similar function losses in addition to a consistent mean subtest weighted score pattern. For those interested in designing scatter-patterns the procedure suggested previously (1, p. 230) still holds: use information weighted score as the basal point for deviation computation of the other 10 subtest weighted scores. The order of deviation of these 10 subtests from information —from most to least deviated—is: digit symbol, digit span, block design, object assembly, and picture arrangement.