Quark-hadron phase transition, QCD lattice calculations, and inhomogeneous big-bang nucleosynthesis.

We review recent lattice QCD results for the surface tension at the finite temperature quark-hadron phase transition and discuss their implications on the possible scale of inhomogeneities. In the quenched approximation the average distance between nucleating centers is smaller than the diffusion length of a proton, so that inhomogeneities are washed out by the time nucleosynthesis sets in. At present lattice results are inconclusive when dynamical fermions are included.