The lasing performance and wavelength tunability of a novel high efficiency copolymer poly[(2, 5, 2‘, 5‘‐tetraoctyl)‐p‐terphenyl‐4,4‘‐ylene vinylene‐p‐phenylene vinylene], TOP‐PPV, pumped with third harmonic radiation of a Nd:YAG laser, was studied in various organic solvents. The results were compared with Coumarin 120 and Coumarin 47 in ethanol under identical experimental conditions. The efficiency of the TOP‐PPV copolymer in hexane exceeds that of both coumarin dyes with more than 50%. The laser emission of the polymer dye in hexane is tunable in the wavelength region between 414 and 456 nm (&Dgr;&lgr;=38 nm). ©1995 American Institute of Physics.