The inhibition action of four amine compounds (e.g. p-toluidine, o-aminophenol, anthranilic acid and o-phenylenediamine) on the corrosion of mild steel in HCl solutions has been studied using weight – loss technique. The results revealed that most of the amine compounds inhibit the corrosion of mild steel. It is obvious that, at each inhibitor concentration the inhibition effect for the amine compounds increases in the following order: anthranilic acid > o-phenylenediamine > p-toluidine. The inhibition effect of anthranilic acid and o-phenylenediamine compounds could be attributed to the formation of an insoluble adsorbed complex layer onto the metal surface, while in case of p-toluidine the inhibition effect was ascribed to the formation of a link between the – NH₂ group and the metal surface via adsorption. On the other hand, different concentrations from o-aminophenol in HCl were found to accelerate corrosion. This stimulating action towards the corrosion of mild steel could be due to oxidative tendency of the formed adsorbed surface complex. The corrosion inhibition mechanism is discussed depending on the nature and surface charge of the metal, the type of the aggressive electrolyte and the chemical structure of the amine compounds.