Mast cells (MCs) were studied quantitatively and qualitatively in the wall of the esophagus (upper, middle and lower portions) of the individuals in the I period of mature age (22-35 years, n = 6) as well as in old and senile persons (61-82 years, n = 10). In all the individuals, the total number of MCs was found to increase from the upper portion of the esophagus towards the lower one. Within the esophageal wall, the total number of MCs decreased in the direction from tunica mucosa towards adventitia. During I period of mature age, the resting MCs filled with granules predominated, while the degranulating MCs were located in the lower esophageal segment. In the individuals of old and senile age, the degranulating MCs were more frequently observed in the upper and lower esophageal segments.