The relationship between vitamin A and carotene of the serum and the lipids of the serum has been stressed in previous communications.1 From the literature it is evident that the vitamin A and the lipids of the serum behave similarly during the course of pneumonia and during convalescence. Thus, it is known that during the course of pneumonia the vitamin A of the serum is reduced sometimes to an extreme degree, though complete absence is rare.2 Likewise during infections the lipids may be reduced and, as in the case of vitamin A, the reduction is likely to be especially great in pneumonia.3 There is some disagreement concerning the level of vitamin A storage in pneumonia, certain investigators claiming to have found a reduction, though usually it was rather slight,4 and others having found none.5 However, it is evident from the published figures that the loss