Age-dependent changes in the entorhinal cortex (EC) and subicular complex (SC) were studied in 30 brains of patients who died between 14 and 86 years of age, without CNS impairment, as determined by macro- and microscopic examination. The brains were fixed in 10% formalin and embedded in paraffin. Three series of coronal EC and SC sections (7 microns) were stained by Nissl, PAS or hematoxylin-eosin. Using neuronal count and Kariometry, age-dependent modifications were studied in layers II, III and V of the lateral area of the EC; in the pyramidal layer of the subiculum (S), and in layer II of the presubiculum (PS). All EC layers studied presented a slight (11-20%) although significant reduction up to 35 years, but from 35 to 75 years the decrease was not significant. After 75 years the neuronal loss increased slightly. The nuclear area decreased up to the age of 40-45 years, (10-18%) and augmented from this age up to 75 years (10-14%). During the last period of life, the nuclear area did not change. From 30-60 years, pyramidal layer in the S showed a significant neuronal loss (30%), thereafter, neuronal reduction was less. At early years, the nuclear area decreased insignificantly (15%), and from 35 years up to the most advanced age studied, it increased significantly (13%). In the PS, layer II manifested a cell loss throughout the lifespan (32.9%) and the changes in the nuclear area did not reach statistical significance due to the dispersions of its values.(ABSTRACT TRUNCATED AT 250 WORDS)