In FeSe_1-xTe_x, the superconducting and magnetic properties can be tuned not only by the Se-Te ratio x, but also by application of hydrostatic pressure. It was seen that both parent compounds FeSe and FeTe are extremely sensitive on hydrostatic pressure and show quite unexpected effects. The at ambient pressure superconducting FeSe exhibits at pressures above 1 GPa a phase, where superconductivity and antiferromagnetism seem to coexist on an atomic scale. The antiferromagnetic FeTe, on the other hand, transforms from a low pressure antiferromagnet to a ferromagnet above 2 GPa. These pressure studies underline the close relation of the electronic phases to the crystallographic properties, since in these simple compounds already minor changes in the structure for example by application of pressure lead to a drastic change of the superconducting and magnetic properties.