A custom testing machine that allows biaxial loading of microtubes under axial force and internal pressure is described. The main components of the machine are a meso-scale tensile stage, a high-pressure pump and a 3D digital image correlation system. The machine is capable of performing both radial (i.e., proportional) and arbitrary (i.e., non-proportional) loading paths in the 1st and part of the 2nd quadrant of the axial-hoop nominal stress space. Results of 14 radial paths in this stress space are reported for stainless steel SS-304L microtubes. The induced strain paths indicated that this material is anisotropic. Also plotted were contours of constant plastic work. It was discovered that the anisotropy of the material evolved at different rates for different loading paths, indicating deformation-induced anisotropy. The results can be used to calibrate anisotropic yield functions for use in numerical simulations of microforming processes.