An investigation of the circulating leukocytes of 2 children with the characteristic clinical features of the Chediak‐Higashi syndrome has revealed a previously undescribed abnormality. Virus‐like particles were found in areas of cytoplasmic degeneration within their white blood cells. Since the particles found were similar in both children and were observed only when they had developed lymphoma, a possible relationship between the known susceptibility to infection and malignancy found in children with this rare disease was suggested. Further, since the granulation anomalies of the circulating leukocytes and the areas of focal degeneration derived from them are lysosomes, the failure of these large granules with acid hydrolase activity to react physiologically in the presence of virus‐like particles may indicate a possible mechanism for recurrent infection and malignant transformation in this disease.