LEAD poisoning in infants and children is, unfortunately, of relatively common occurrence. In the past nine years, 95 cases have been observed in the Infants' and Children's Hospitals of Boston, and in the past twelve months (to September, 1933) 19 patients were admitted to the hospital with symptoms of intoxication directly attributable to this cause. It is not within the scope of this paper to discuss in detail the etiology and clinical features of the disease. An extensive résumé of lead poisoning has been published by Aub and his co-workers and recently a review of the manifestations of the disease in children has appeared (1, 8). However, a brief description of the sources of lead and symptomatology, together with an evaluation of certain special signs and tests, is desirable in determining the proper place of the roentgenologic findings as aids in the diagnosis. Sources of lead Lead poisoning in children is due usually to the ingestion of lead paint, chewed by the child from the toys, crib, or woodwork of the house. Small amounts of lead in drinking water may lead to intoxication. We have seen one case of lead poisoning following the eating of fruit which had been sprayed with lead arsenate. In infants, prolonged use by the mother of lead nipple shields (14) or the application to the breasts of lead acetate ointment has resulted in intoxication. In Japan, poisoning of infants has occurred frequently from the use by the mother of face powder containing lead (3, 4, 5). Recently an extensive series of cases has been reported of poisoning following the inhalation of fumes in homes where casings of storage batteries were used as fuel (15). The development of symptoms following the ingestion or inhalation of lead appears to depend upon the age of the child, the amount of lead absorbed, and the period of time over which it is taken in, as well as individual variation in tolerance. The poisoning by lead of all the young patients we have seen has been a gradual process. Whether from paint, water pipes, or nipple shields, the ingestion of small amounts of the metal has gone on for weeks or months before the patient was brought for medical attention. Thus we usually see the culmination in acute symptoms of what is actually a chronic poisoning. When lead is absorbed it is probably carried to all parts of the body, the major portion soon being deposited in the bones in inert form (1). However, lead as well as other minerals is always in a state of flux between deposition and resorption; small amounts are constantly being eliminated. Under certain circumstances the lead deposited in the bones may be mobilized again to enter the circulation and cause symptoms of disease. A patient whose bones contain deposits of lead may be spoken of, therefore, as having latent lead poisoning. Acute, febrile illnesses or acidosis appear to be the important factors influencing the mobilization of lead.