  We present the first infrared interferometric observations of a young stellar
object with a spatial projected resolution better than 2 AU. The observations
were obtained with the Palomar Testbed Interferometer. FU Ori exhibits a
visibility of V^2 =0.72 +/- 0.07 for a 103 +/- 5 m projected baseline at lambda
= 2.2 microns. The data are consistent on the spatial scale probed by PTI both
with a binary system scenario (maximum magnitude difference of 2.7 +/- 0.5 mag
and smallest separation of 0.35 +/- 0.05 AU) and a standard luminous accretion
disk model (approx. accretion rate of 6e-5 Mo/yr) where the thermal emission
dominates the stellar scattering, and inconsistent with a single stellar
photosphere.
