We report a novel and potentially generic method for the efficient patterning of films of organic semiconductors and demonstrate the merit of the method on the high-solubility fullerene [6,6]-phenyl C-61-butyric acid methyl ester (PCBM). The patterning technique is notably straightforward as it requires no photoresist material and encompasses only two steps: (i) exposure of select film areas to visible laser light during which the PCBM mononer is photochemically converted into a dimeric state, and (ii) development via solvent washing after which the nonexposed portions of the PCBM film are selectively removed. Importantly, the method is highly benign in that it leaves the electronic properties of the remaining patterned material intact, which is directly evidenced by the fact that we fabricate fully functional arrays of micrometer-sized field-effect transistors with patterned PCBM as the active material.