Raman scattering of 5145‐Å argon laser radiation by two magnons in the perovskite antiferromagnet KNiF3has been observed. At low temperature, the spectrum of the scattered light is in excellent agreement with a Green's function theory for a perovskite withS= 1 and nearest‐neighbor exchange constantJ= (71.0±0.8) cm−1. If the effects of anisotropy (obtained from far‐infrared antiferromagnetic resonance measurements) are included, the value ofJis changed only slightly, decreasing ≈0.5 cm−1. The line shape and position were also observed as functions of temperature. A comparison is made with similar scattering observed inRbMnF3 (S=52)and in related magnetic Ni2+fluorides.