Results of trials in which cattle were infected by endotracheal intubation of Mycoplasma mycoides var. mycoides small colony (MmmSC) cultures or by contact exposure to animals affected by contagious bovine pleuropneumonia (CBPP) are numerous. However, an analysis of the effects of the two different routes of infection on disease outcome is lacking. This study analyses the disease outcome in cattle infected by the two methodologies. Data originate from two controlled trials conducted in Namibia under field conditions. Intubation appears to be responsible for chronic evolution of the disease while in-contact infected animals develop more severe infection inducing mortality. Our results seem to suggest that the mode of infection may condition the disease outcome and should be taken into consideration in studies on the pathogenesis of CBPP.