The postal service has of course a mission of delivering mail to the whole population — the obligation of reaching it via postal rounds — the constraints on the location of the post offices are a lot vaguer. A comparison of the distribution of post offices and banks in the “Seine-Maritime” County taken as an example not only shows a difference in the density of the establishments, but mainly a different location principle. The suggestions presented, for post offices relocations, are based on the only simple, clear and easily checked criterion of the minimization of distance between the client’s home and the post office. The possible locations which are currently lacking post offices have been mainly determined in function of the commercial districts currently lacking post offices. The results of the model allow the starting of some reflection on the relocation of post office establishments.