This work aims at assessing at molecular level the effect caused by the HgCl9 intercellular communication inhibition at non-cytotoxic doses. On the basis of our previous experiences, we exposed the human keratinocytes (HUKE) at 10 nM of HgCl2 for 24 hours Next, we estimated: a) the protein expression of connexines Cx43, Cx32 and Cx26 by western blotting; b) the amount of mRNA corresponding to the three connexines by semi-quantitative RT-PCR; and c) the production of reactive oxygen species in HgCl2 treated cells using a specific probe, i.e. DCF in confocal microscopy. Our study demonstrated a higher expression of the transcripts for Cx26, Cx32, Cx43, and a higher amount of proteins Cx43, Cx32 and Cx26, compared to the negative controls. Furthermore, we studied the effect of HgCl2 on the ROS production in keratinocytes, by the analysis in confocal microscopy carried out with the DCF, fit for marking the oxygen free radicals. In HgCl2 treated keratinocytes we obtained an increase of the ROS production compared to controls; and further the mitochondrions resulted the place of ROS production. The results of this study suggest that non-cytotoxic HgCl2 concentrations, might cause an unbalancing of the redox cellular state (ROS increased level), and we can assume that the activation of a redox signalling involves the inactivation of gap junctions.