  In this article we discuss lepton asymmetry effect on BBN with neutrino
oscillations. We argue that asymmetry much smaller than 0.01, although not big
enough to influence directly the nucleosynthesis kinetics, can effect
considerably BBN indirectly via neutrino oscillations. Namely, it distorts
neutrino spectrum and changes neutrino density evolution and the pattern of
oscillations (either suppressing or enhancing them), which in turn effect the
primordial synthesis of elements. We show that the results of the paper X. Shi
et al., Phys. Rev. D 60, 063002 (1999), based on the assumption that only L >
0.01 will influence helium-4 production, are not valid. Instead, the precise
constraints on neutrino mixing parameters from BBN are presented.
