The magnetic properties of HDDR permanent magnets prepared from alloys with a nominal composition of RE 1 3 . 7 Fe 6 3 . 5 Co 1 6 . 7 B 6 Zr 0 . 1 (RE: Pr and Nd) have been assessed using a permeameter technique. HDDR powders from the alloy in the as-cast and annealed (1100 o C for 20 h) conditions were isostatically pressed and bonded in wax before testing. It has been shown that it is possible to produce highly anisotropic HDDR material from the Pr 1 3 . 7 Fe 6 3 . 5 Co 1 6 . 7 B 6 Zr 0 . 1 alloy in the annealed state, whereas the corresponding Nd 1 3 . 7 Fe 6 3 . 5 Co 1 6 . 7 B 6 Zr 0 . 1 HDDR material prepared under the same conditions, did not exhibit any significant permanent magnetic properties. The microstructures of both as-cast and annealed alloys have been investigated by scanning electron microscopy and energy dispersive X-ray analysis in an attempt to reveal the reason for this behaviour. Thermomagnetic analysis using in-situ magnetisation measurements have also been carried out on the alloys.