A unifying concept, that the impairment of connectives tissue, owing to the effect of immigrant cells, is at the basis of the pathogenesis of Vitamin A deficiency has been considered. Changes in various tissues and organs have been reviewed in the light of the recent discoveries in the field of histology (1). An effort has been made to link the various symptoms of Vitamin A deficiency to those related to other pathologies where connective tissues are involved, and to suggest a plan for research to be undertaken to achieve a better knowledge of the etiology of Vitamin A deficiency.