The aim of this work was to study the transfer through the intestinal barrier of two polycyclic aromatic hydrocarbons (PAHs) (benzo[a]pyrene and phenanthrene) and a dioxin (2,3,7,8-tetrachlorodibenzo-para-dioxin) which differed in their physicochemical properties. Both in vitro and in vivo assays were performed. For the in vitro study, Caco-2 cells, cultivated on permeable filters, permitted to measure the transepithelial permeability of the studied $^{14}$C-labelled molecules. For the in vivo study, portal absorption kinetics were evaluated in pigs fed contamined milk. The results showed that all the molecules were absorbed and demonstrated a differential intestinal absorption for the studied molecules. Phenanthrene appeared to be the fastest and most uptaken compound, followed by benzo[a]pyrene and finally 2,3,7,8-tetrachlorodibenzo-para-dioxin. Their absorption levels were respectively 9.5, 5.2 and 1.4% after a 6 h-exposure in vitro and 86.1, 30.5 and 8.3% in vivo for the 24 h following ingestion. These findings suggest that the physicochemical properties of the xenobiotics and intestinal epithelium play key roles in the selective permeability and in the bioavailability of the tested micropollutants.