The Schoenlein-Henoch syndrome is described on the basis of 44 personally observed cases. It is defined as a condition in which nontraumatic hemorrhage with or without edema may occur in the skin, or subcutaneous tissue, or joints, or viscera, or in any combination of them, and in which the blood platelets are normally abundant. The causes of the syndrome are varied, but streptococcal infection is important, and "anaphylactoid" causes rare. The prognosis is good, and the 4 cases with renal involvement also did well. Schoenlein-Henoch purpura and purpura simplex overlap, but in contrast with the latter, Schoenlein-Henoch purpura is not familial, and is common in males and children.