Impaired function of the human intestinal epithelial barrier (IEB) might allow for permeability of harmful substances, such as obesogens, which induce obesity and further implications. Tight junction (TJ) proteins are the key component for normal functions of the barrier. In this master thesis, the correlation between increased TJ permeability of the IEB and absorption of obesogens was studied. The effect of obesogens on TJ expression was also investigated. Permeability tests performed on Caco-2 cell monolayers exposed to obesogens showed altered permeability, indicating that obesogens might have an effect on TJ protein expression. Furthermore, impaired monolayers showed increased permeability, which implies that impaired functions of IEB lead to increased absorption of obesogens.