The scientific interest in the influence of xenobiotics on the human body is due to the fact that immune organs are characterized by a pronounced response to the influence of endogenous and exogenous factors. Recently, the immunological impairment, as a manifestation of reactions to ecopathogenic conditions, suggests a major pathogenesis role in the development of cardiovascular, neuropsychiatric diseases, as well as diffuse diseases of connective tissue. Objectives - experiment was designed to elucidate the organometric changes in thymus of male rats due to impact of propylene glycol. 40 WAG matured male rats were divided randomly into two groups. The first group served as a control and constituted 8 animals. The second group of 32 rats, 8 rodents in each, were treated via gavage by aqueous solutions of propylene glycol in doze 1/10 LD50 in conversion to 26,38 g/kg during 7, 15, 30, 45 days. All animals were sacrificed on the term defined by experimental design. Thymus specimens were dissected out, and linear dimensions (length, width, height) using digital caliper were measured, along with mass and volume of the thymus. Limits of the thymus morphometric indices' variability in intact and experimental groups were calculated. The research indicates that exposure to propylene glycol caused marked organometric changes in rats' thymus. However, more pronounced changes were observed on 7th and 30th days. Were established the following limits of variability indices oscillations: IndHL of the experimental group thymus ranged from min=12.57 to max=47.54, the mean value was from 24.67 to 28.02; IndHW of the experimental group thymus ranged from min=11.96 to max=88.73, the mean value was from 36.78 to 41.41; IndT of the experimental group ranged from min = 38.17 to max=141.3, the mean value was from 71.1 to 86.52. The study of the morphometric parameters of the thymus in the experimental group of rats has established a significant reduction of all parameters and their deviation from the parameters of the control group, that shows active reaction of thymus on induced xenobiotic.