Metal octaethylporphyrin M(OEP) (M = Ni, Cu, Zn, Pd, Ag, and Pt) nanowires are fabricated by a simple solution-phase precipitative method. By controlling the composition of solvent mixtures, the diameters and lengths of the nanowires can be varied from 20 to 70 nm and 0.4 to 10 microm, respectively. The Ag(OEP) nanowires have lengths up to 10 microm and diameters of 20-70 nm. For the M(OEP) nanowires, the growth orientation and packing of M(OEP) molecules are examined by powder XRD and SAED measurements, revealing that these M(OEP) nanowires are formed by the self-assembly of M(OEP) molecules through intermolecular pi...pi interactions along the pi...pi stacking axis, and the M(2+) ion plays a key role in the nanowire formation. Using the bottom contact field effect transistor structure and a simple drop-cast method, a single-crystal M(OEP) nanowires-based field effect transistor can be readily prepared with prominent hole transporting behaviour and charge-carrier mobility up to 10(-3)-10(-2) cm(2) V(-1) s(-1) for holes, which are 10 times higher than that of vacuum-deposited M(OEP) organic thin-film transistors (OTFTs).