  We report on study of the electronic anisotropy of the newly discovered MgB2
superconductor using the in-plane resistivity measurements in magnetic field
applied perpendicular and parallel to Mg and B planes of MgB2 single crystals.
The results show temperature dependent anisotropy of the upper critical field
with anisotropy ratio increasing from 2.2 close to Tc up to about 3 below 30K.
Our estimation of the in-plane and out-of-plane coherence length of about 68A
and 23A and electronic mean-free path 240A and 60A respectively indicates MgB2
single crystal as approaching clean limit type-II superconductor.
