In this paper, the dependence of the crystal radius on the pulling rate (v), melt temperature at the meniscus basis (T 0 ), pressure in the furnace (p) and die radius (r 0e ) is found. Using these dependences, those values of v, T 0 , p and r 0e are found for which the crystal radius variation due to small uncontrollable variations of v, T 0 , p around some average values causes minimal surface non-uniformities. Numerical results are given for an Nd:YAG cylindrical bar grown in a furnace in which the vertical temperature gradient is k=33(K/mm).