In this paper the results of the calculations of the roughening transition temperatures of anisotropic and (pseudo) hexagonal lattices are presented. The calculations are based upon a so-called Ising lattice combined with a simple model for the representation of the lattice. The lattice has three different bonds of which for two the relative strengths are varied. The Ising transition temperatures have been calculated for different lattices and for the case of orthorhombic n-paraffin crystals they have been compared with experimental values obtained from vapour growth experiments.