Gau M, Konishi K, Takasawa K, et al. - Given that one of the major objectives of newborn screening for 21‐hydroxylase deficiency (21OHD) is preventing life‐threatening adrenal crisis, however, the details of adrenal crisis in newborns are not well known, researchers sought to clarify the clinical details of salt‐wasting in newborn 21OHD patients. They retrospectively analyzed the conditions of classical 21OHD neonates before the initiation of therapy based on the follow‐up survey of the screening in Tokyo from 1989 to 2017. One hundred classical 21OHD patients (55 male, 45 female) have been analyzed. The data showed that the risk of developing severe salt‐wasting (SSW) increases during the second week of life without a threshold, and for preventing SSW, early intervention, preferably during the first week of life, is desirable. Increased body weight during the second week of life suggests a lack of SSW.