Abstract We report a systematic study of the generation line polarization of optically pumped Laser Induced Plasma Lasers. Results are presented for the elements of the 13th group with ground state configuration ns np 2 P 1∕2 ; 3∕2 . Degree of polarization depends on pumping light polarization, spin states of ground, and pumped electronic levels. The external magnetic field directed perpendicularly to the magnetic vector of a plasma laser strongly reduces its degree of polarization. It is proposed that the self-generated magnetic field induced by the pumping beam in the plasma is responsible for the polarization effects. The strength of this self-generated magnetic field is about 200 mT.