Reflection high‐energy electron diffraction (RHEED) is used to determine the local misorientation of vicinal, molecular beam epitaxy prepared GaAs surfaces. With the glancing angle of incidence fixed, the intensity along the (00) streak is measured for different crystal azimuths. The specular beam is observed to split by an amount that depends upon the scattering geometry and surface misorientation. The method is applied to surfaces misoriented with respect to low‐index bulk planes by an average polar angle of 2°, 1°, and 5 mrad. Local polar and azimuthal misorientations were determined to within 5% and 10°, respectively. The measurement shows that an important mechanism responsible for RHEED streaks is diffraction from ordered staircase steps.