Perspective. We regret that several printer’s errors occurred in the article by Robert Gallo, which appeared in number 15, July 20, 1999, of Proc. Natl. Acad. Sci. USA (96, 8324–8326): (i) In both the Table of Contents and the paper itself the title should read: “Tat as one key to HIV-induced immune pathogenesis and Tat toxoid as an important component of a vaccine.” (ii) In the paper, the standard abbreviation IFN-α should be consistent throughout, but it appears incorrectly as INF-α on page 8324 in lines 27, 28, 29, and 43. We apologize for these errors.