Evolutions of profiles for a cylindrical specimen during hot compression were calculated with finite element methods. The calculations have been carried out with different characteristics of flow behaviors for the alloy 16CrMo4. Variations in the maximal radius of the specimen are determined predominately on geometric factors of the compression, while indifferent to magnitudes as well as strain hardening rates of flow stresses. This result was verified by hot compression testes of two different alloys employing Gleeble experiments. The increment of the maximal radius within a definite strain range is enhanced by introducing significant temperature gradients.