In the article by Dr. Josef Warkany, "Estimation of Vitamin D in Blood Serum," in the October 1936 issue (Am. J. Dis. Child. 52:831, 1936), two errors occurred: On page 833, in the fourth line of the second paragraph under "Method," "30 per cent" should have read "20 per cent." In tables 1, 2, 3, 6, 7, 8, 9, 10, 11 and 12, the heading "Vitamin D content of Rat's Serum" should have read "Vitamin D Content of Rabbit's Serum."