Wehave successfully used nulling interferometry at 10 #mwavelength to interferometrically suppress a star's radiation. This technique was #rst proposed by Bracewell 20 years ago to image extra-solar planets 1 and is now the basis for proposed space-borne instruments to search for Earth-like extra-solar planets and their spectroscopic signatures of habitability and life 2;3;4 . In our experiment, the beams from two 1.8 m telescopes of the Multiple Mirror Telescope were broughtinto registration at a semi-transparent beamsplitter, and the images made coincidenton an infrared array detector capable of taking rapid short exposure images. The atmospheric #uctuations caused the phase di#erence between the beams to #uctuate, changing the total #ux of the star seen in the image plane. When the atmosphere caused the wavefronts to be exactly out of phase the entire stellar Airy pattern disappeared. For the unresolved star # Tauri the cancellation was such that a companion only 0.2 arcsec fro..