The solidification behaviour and resultant microstructures of bulk glass forming ferrous (Fe60CoSZr10Mo5W2B15) and non-ferrous (Zr65Al10Ni10Cu15) alloy systems have been investigated. It was shown that the suppression of the eutectic reaction during solidification ultimately leads to the formation of an amorphous structure. The characteristic DSC pattern of melting involving a sequence of eutectic and pefitectic like reactions with a high inapitude of reaction enthalpies ratio (AHp/AH,). appear to be essential parameters for high hulk- glass forming ability. (C) 2004 Elsevier B.V. All rights reserved.