The stellate ganglia of eight patients died in the course of severe pulmonary tuberculosis were examined in order to study the degree and the type of ganglionar reaction. The changes were of the proliferative type, especially hyperplasia and hypertrophy of dendrites, features of argentic balls being found. Not merely the neurons were damaged but also the ganglionar fibers showed greater affinity for the silver salts, tortuosities and nodosities, ending sometimes in pathologic buttons. These fibers, which frequently end in pathologic neurons, establish gross and strongly impregnated connections with the dendrites. The changes are seen isolated or in groups, in the neurons of similar size and morphologic features (isodynamic groups); this fact is important because it points to neuronal reaction in cells possibly assembled to perform identical functions. The mesenchyma shows lesions, mainly alterations of the inflammatory type: dilated vessels with thickened walls and blood stasis, swollen endothelial cells, sometimes with granules in the cytoplasm.