Cryptophanes represent an exciting class of xenon-encapsulating molecules that can be exploited as probes for nuclear magnetic resonance imaging. The 1.70 angstrom resolution crystal structure of a cryptophane-derivatized benezenesulfonamide complexed with human carbonic anhydrase 11 shows how an encapsulated xenon atom can be directed to a specific biological target. The crystal structure confirms binding measurements indicating that the cryptophane cage does not strongly interact with the surface of the protein, which may enhance the sensitivity of Xe-129 NMR spectroscopic measurements in solution.