The identification of viral particles in the lymph node germinative centers from patients at risk for AIDS is an important diagnostic factor in the prodromal stages of this illness. Those particles are solely seen between the cytoplasmic extensions of the dendritic reticular cells. They have the same morphology than LAV-HTLV III virus, incriminated retrovirus in the etiology of the disease. They were found in 26 of the 30 lymph nodes studied.