Continuous carbon ®bre preforms (M40), with an average ®bre content of 66 vol.-%, were in®ltrated with liquid Mg by gas pressure at various temperatures and pressures in order to determine a relationship between manufacturing conditions and the mechanical properties of the material. A saturation curve describes the in®ltration behaviour of liquid Mg into the preforms and the relationship between in®ltration pressure, pore volume, and mechanical properties. The maximum bending strength of the composites exceeds 1400 MPa and is insensitive to melt temperature between 680 and 720³C. The density of the Mg composite is 1 . 77 Mg m 23 , 20% lighter than the Al ± C composites produced and tested by the authors in an earlier investigation, but yields the same mechanical properties in bending tests at room temperature.MST/4606