In a study using a newly-reported staining technique, malignant cells demonstrated a reaction different from normal cells. The study consisted in the examination of the blood smears of 43 patients with the clinical diagnoses of Hodgkin’s disease, leukemia, lymphoma, lymphosarcoma and some of questionable diagnosis. The cellular reaction was compared to subjects considered normal. In the patients with a diagnosis of a malignancy of the blood, the involved blood cells demonstrated cytoplasmic particles after staining. Included in this reaction were active polymorphonuclear leukocytes. All normal subjects had polymorphs clear of deposition. The cellular reaction was similar to that found in viremias, but unlike the case of viremias the sequence of events in the plasma was completely absent in these malignancies. In the plasma of the reported cases of malignancies of the blood, stable clusters of particles were found. The significance of the cellular similarities and plasma differences between malignancies and viremias are being investigated. The appearance of plasma deposition, different from the viremic plasma phenomenon, may be of diagnostic significance. The possible usefulness of the reported technique in the etiology of cancer was suggeste