The correspondence of S. A. S. Simpson and J. F. Tait with T. Reichstein during their collaborative work on the isolation and elucidation of the structure of electrocortin (later aldosterone)11Professor Tadeus Reichstein died on August 1, 1996 at the age of 99. This account, summarizing and commenting upon the correspondence exchanged between T. Reichstein and ourselves during the isolation and identification of aldosterone, is our tribute to him. In addition to the account of the collaborative scientific work, which again demonstrated his supreme skill in steroid chemistry, this account illustrates his unfailing courtesy to two rather inexperienced workers in the field.