Results are presented for six nuclei from Be to Pb on the structure function ratios F2A/F2C(x) and their A dependence in deep inelastic muon scattering at 200 GeV incident muon energy. The data cover the kinematic range 0.01 < x < 0.8 with Q2 ranging from 2 to 70 GeV2. The A dependence of nuclear structure function ratios is parametrised and compared to various models.