The room temperature photoluminescence and excitation spectra of Bi 3+ in the (Y,Gd) 3 (Al,Ga) 5 O 12 garnets is reported and analyzed. The luminescence spectra of these materials under 1 S 0 → 3 P 1 Bi 3+ excitation consist of two bands in the UV and the visible spectral regions. The UV emission band is attributed to the 3 P 0,1 → 1 S 0 emission of isolated Bi 3+ ions and is observed for the first time in garnet host lattices. Previous reports of Bi 3+ luminescence in (Y,Gd) 3 Ga 5 O 12 garnets only reported the visible emission and attributed this emission to an impurity trapped exciton, implying a strong interaction between the host lattice conduction band and the Bi 3+ excited states. We disagree with this interpretation of the visible emission band. Our results show a strong dependence of the visible band intensity on the Bi 3+ concentration and lead us to conclude that this emission is related to Bi 3+ pairs and/or clusters in the garnet host lattice. There does not appear to be any interaction between the host lattice conduction band and the 3 P 0,1 excited states of Bi 3+ .