The NMR solution structure of calyculin A (1) in chloroform exhibits intramolecular interactions, resembling the original crystal structure1. In methanol, calyculin A has the hydrogen bonding moieties solvent exposed. Dephosphonocalyculin A in chloroform resembles calyculin A in chloroform and the crystal structure of calyculin A. Dephosphonocalyculin A in methanol resembles calyculin A in methanol. The NMR solution structures of calyculin A (R  PO3H2) and dephosphonocalyculin A (R  H) in chloroform and in methanol are reported.