Twelve institutionalized senile patients with a mean age of 75.1 yrs. were used as subjects in this study. Their performance on the Wechsler-Bellevue Adult and Adolescent Intelligence Scale and on the Goldstein and Scheerer Objective Sorting Test was compared with the performance of 5 schizophrenics. The majority of the senile patients were unable to sort objects on the basis of conceptual or abstract principles, but were limited to concrete bases of use and reality in a non-immediate situation in their classification of objects. Their object sortings were qualitatively similar to those of the schizophrenics. This behavior bore little or no relation to the patient''s level of ability as measured by the verbal portion of the Wechsler-Bellevue Scale. As a matter of fact, both senile and schizophrenic groups could classify on an abstract verbal level in the similarities part of the Wechsler-Bellevue Scale when they were unable to sort objects on an abstract or conceptual basis. It seems that patients may use what appears to be an abstract verbal concept with a much more restricted meaning. There seemed to be a hierarchy of ability among senile patients in the Object Sorting situation, dependent upon the number of possible bases of sorting in each group of objects. When the possibilities were sufficiently limited they were capable of identifying relationships, but solely of a concrete type. Intelligence level is not a factor which facilitates sorting. 8 subjects with I.Q.''s within or above average range were unable to sort at an abstract level; a few others with low I.Q.''s could. Most of the senile subjects experienced great difficulty on the Performance Scale of the Wechsler-Bellevue as well despite high scores on the Verbal Scale. The response of the schizophrenic subjects did not reflect this inability to handle performance materials, and their performance scores and verbal scores were quite comparable. There seems to be some indication of the existence of a qualitative difference in the loss of function in senile deterioration compared to that in schizophrenia.