Bright green (at 525 and 550nm) and red (at 660nm) luminescence in Er:Yb:La 3 Ga 5.5 Ta 0.5 O 14 (LGT) powder synthesized by solid state reaction was obtained by pumping at 936nm. Yb 3+ –Er 3+ energy transfer processes accounting for population of the 2 H2 11/2 , 4 S 3/2 and 4 F 9/2 Er 3+ levels are discussed. The dependence of ratio between the intensities of the green and red luminescence on pump intensity is analyzed. The rather high quantum efficiency (58%) of the ( 4 S 3/2 , 2 H2 11/2 ) Er 3+ emitting level recommends LGT doped with erbium and ytterbium for upconversion applications.