Abstract
In this paper we review the work done to obtain measurements of the atmospheric turbulence at the ground level in the Observatorio Astronómico Nacional at San Pedro Mártir. We argue, from recent results obtained during more than a decade, that the median seeing is 0.55 arcsec at a height of 15 m. This analysis confirms that San Pedro Mártir is one of the best ground-based places in the world as far as seeing is concerned and that it is problably the best one.