Age-related changes of human pineal gland were studied morphologically on 168 autopsy cases. Pineal weight in the formalin-fixed condition was 99 +/- 56 mg in males (n = 88, mean age 78 years) and 91 +/- 41 mg in females (n = 80, mean age 79 years), which showed no sexual difference (P = 0.290). There was no correlation between pineal weight and age of the patient (r = 0.0678, P = 0.191, n = 168). The pineal volume calculated as a spheroid was directly proportional to the weight (r = 0.904, n = 167, P = 0.000). A significant correlation existed between pineal weight and the degree of calcification (r = 0.231, P = 0.002, n = 156). The density of the pineals decreased with age (r = -0.164, P = 0.017, n = 167). The degree of calcification and cyst formation did not increase with age, but the grade of cyst formation was related to the pineal volume (P = 0.0002). Some pineals of the patients over 90 years old showed no calcification and appeared indistinguishable from the ones of the younger subjects. The weight and volume of the pineals of the patients with hypertension was appreciably greater than those of the non-hypertensive patients. These results indicate that human pineals do not necessarily degenerate progressively after involution.