We present a crystallization study of melt‐spun Fe‐Zr metallic glasses. Unlike Cu‐Zr and Ni‐Zr, the immediate crystallization products cannot be understood in terms of the equilibrium crystalline phase diagram: all are metastable or unstable phases. In the composition range Fe25Zr75to Fe33Zr67, there is evidence that explosive crystallization occurs. The behavior of the activation energy with composition suggests there may be a eutectic at the composition Fe37.5Zr62.5.