Clinical observations suggest that lipoid nephrosis is produced by a systemic abnormality of T-cell function resulting in the secretion of a circulating chemical mediator toxic to an immunologically innocent glomerular basement membrane. The lack of evidence of a humoral antibody response, remission induced by measles which modifies cell-mediated immunity, the therapeutic benefits of steroids and cyclophosphamide which also abate cell-mediated responses, and the occurrence of this syndrome in Hodgkin's disease support this hypothesis The susceptibility of untreated patients to pneumococcal infections may be of primary or secondary pathogenetic importance. Taken together, the data sugges that this syndrome is a clinical expression of a self limited primary immune-deficiency disease.