Macro defect free (MDF) cements were invented by Birchall et at in early 1980s. MDF cements are cement-polymer composites and have special production techniques, such as calendering between the rollers, by which a kind of shear mixing is applied The most Important property of MDF cements is their extraordinary high flexural strengths, in spite of being cement-based materials. The most widely used cement and polymers in the production of MDF composites are calcium alumina cements (CAC) and poly(vinylalcohol) (PVA), respectively. However, Portland cement as cement and phenol resin as polymer were also tested successfully in MDF production. The Al(2)O(3) content of cement seems an important factor on strength properties of MDF composites. Also hydrolysis degree of PVA influences the strength properties. The weak point of MDF composites is their low durability in moisture environment Many attempts have been tested to overcome this problem In this study, the effect of alumina content of high alumina cement, hydrolysis degree of PVA, desolving method of PVA and addition of some additives are discussed. Also investigated was the surface morphology of MDF composites.