A new rabbit model to study the consequences of splenectomy in host resistance to induced pneumococcal septicaemia is presented. A simple, fast, non-invasive and complication-free technique of bacterial inoculation into the rabbit airways, using transcutaneous cannulation of the trachea, is also described. Sixteen normal and 24 splenectomised animals were used. The optimal dose of pneumonococcus (serotype B, type III) was found to be 1 x 10(7) organisms. The above dose of bacteria given transtracheally failed to cause signs of pneumonia or death in any of the normal rabbits. However the same dose introduced using the same technique resulted reproducibly in the death of the low-resistance splenectomised animals.