We demonstrate spin pumping and inverse spin Hall effect (ISHE) in an all oxide heterostructure composed of two oxides with different respective crystal structures. Y3Fe5O12 (YIG) is used as a spin source, being a perfect candidate because of its low damping and insulating behavior. SrRuO3 (SRO), a perovskite oxide with metallic conductivity, serves as a spin sink. Spin pumping is shown by the increase of the damping in ferromagnetic resonance for the YIG in the presence of an SRO top layer and by the inverse spin Hall effect appearing in the SRO. Transmission electron microscopy shows that the growth of YIG is fully epitaxial, while the SRO grows in islands of several polycrystaline phases, a fact which strongly influences the measured ISHE. The magnetization of the YIG remains unaffected by the SRO layer while the SRO no longer shows the low temperature ferromagnetism typically observed in monocrystalline layers.