Er and Cr doped ß-Ga_2O_3 nano- and microwires have been grown by thermal treatments of Ga2O3 powder containing a fraction of Er_2O_3 powder or in the presence of Cr_2O_3 powder, respectively. Doping gives rise to the characteristic red photoluminescence (PL) of Cr^3+ ions at about 700 nm and to green emission of Er^3+ at about 555 nm. Waveguiding of the ion related PL light excited in the wires has been studied for wires with different sizes. Waveguide behavior for incident visible light of different wavelengths was demonstrated.