We demonstrate fabrication of rubrene-Co nano-composites, yielding an introduction of a spin degree of freedom in rubrene-based, electronics devices, and report on large magnetoresistance (MR) ratio of 78% at 4.2 K. It is elucidated that the observed MR effect is ascribed to the magnetization of the Co nano-particles, and this indicates spin-dependent transport via rubrene molecules is achieved. In addition, the MR effect can be observed even at room temperature. (c) 2007 Elsevier B.V. All rights reserved.