Coherent emission at 5540, 5617, and 7037 Å from Er3+ions in BaY2F8is reported. Oscillation at 5540 Å takes place at 77°K in a transition from4S3/2to a level of the4I15/2ground state at 406 cm−1. The line at 5617 Å is produced in a transition from2H9/2to a level of4I13/2at 6740 cm−1, and 7037 Å is generated in a transition from2H9/2to a4I11/2level at 10 336 cm−1. Pumping of the4I13/2state results inQswitching of the output at 5540 Å. The conditions required to produce oscillation in these lines and the detrimental effects of Yb3+are discussed.