The results of magnetic measurements performed on ZrCo5.1-xFex alloys in the temperature range 4.2-900 K and fields up to 7 T are reported. The presence of solid solutions is evidenced in the composition range x < 0.9. The Curie temperature and the saturation magnetization increase nearly linearly when cobalt is substituted by iron. In addition, the anisotropy field decreases and shows an unusual temperature dependence, with a maximum at T congruent-to 300 K.