Among the 14 cases of antibiotic-induced colitis, endoscopic features were: in 9 cases typical pseudomembranes, in 4 cases petechiae or ecchymosis or suggillation-like redness with near-to-normal surrounding mucosa. In one case induced by Spiramycin, a macrolide that had never been previously indicated as being responsible for the disease, the endoscopic picture was 'atypical' and directed us towards a severe ulcerative colitis. These forms are very rare and usually limited to the right or transverse colon which suggests, if possible, a total colonoscopy. The nosographic picture of these cases is not quite clear, since they could represent both the most severe stages within 'non-pseudomembranous' antibiotic-induced colitis and autonomous forms whose evolution does not contribute in any way to the formation of pseudomembranes.