The aim of the study was to determine the bronchial segmental tree dimensions of lower lobes in humans and Cercopithecus aethiops and to estimate the possible relations between them. The study was carried out on a group of 62 human cadavers (aged 20 to 60; 28 men, and 34 women) and 30 sexually mature corpses of Cercopithecus aethiops (14 male and 16 female individuals). The trachea and bronchi were swilled out, injected with duracryl and digested in hydrochloric acid. After washing out an exact model of the topographically unchanged bronchial tree was obtained. Those preparations were dried and the diameters of the segmental bronchi in the lower lobes of both lungs were measured. The statistical analysis was performed using the SAS system v. 6.11. Differences between groups were analyzed by ANOVA. If P < 0.05, differences between the mean values were considered statistically significant. In the studied material almost all measured values in Cercopithecus aethiops were higher in female individuals in contrast to the results obtained for humans. In both sexes of Cercopithecus aethiops medial and anterior basal bronchi have the biggest diameter in both sides, but in male and female humans posterior basal bronchus has the biggest diameter. Unlike humans, where the medial segments are small, the medial segments in Cercopithecus aethiops constitute a significant functional part of the lungs.