The spin-wave excitation spectrum of ferromagnetic DyAl₂ has been measured at 5K by neutron inelastic scattering methods. The scattering at selected momentum transfers has also been measured at elevated temperatures. The results are used to obtain crystal-field terms and exchange interactions. Strong magnon-phonon coupling effects occur. At elevated temperatures the spin waves exhibit considerable lifetime effects well below T_c and an excited-state spin wave is observed.