The authors report on two cases of pseudomembranous colitis (P.M.C.) developed in two Senegalese women of 38 and 36 years, and discovered at the 4th and 5th day respectively of an antibiotherapy based on ampicillin. In these two observations, cysts of Entamoeba histolytica histolytica were found in both feces and biopsies. They recall the circumstances of the occurrence, diagnosis techniques and treatment. They underline the unfrequency of this disease in Africa south of Sahara and they discuss the correlation with amoebiasis colitis. One has to keep in mind the possibility of a P.M.C. during any antibiotherapy, and consequently to have a rectoscopy to perform. Such an exploration is enough to pose a diagnosis. In day to day practice it is not necessary to show clearly the specific germ Clostridium difficile or its entero-toxin. To stop any antibiotherapy is required and beneficial. Metronidazole or Vancomycin are the best drugs in this case.