Complete H-1 and C-13 assignments of 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578) in DMSO-d(6) were made using H-1, C-13, DQCOSY, ROESY, TOCSY, HSQC and HMBC spectra. Comparing the assignments with those of rapamycin showed that in the published C-13 assignments of rapamycin in DMSO-d(6) the shifts for C-12 and C-42 have been interchanged, as well as the shifts for C-1 and C-8. Copyright (C) 2004 John Wiley Sons, Ltd.