Mass spectrometry of intact synthetic polymers has been limited to ®eld desorption (FD) MS for many years. More recently, soft ionization techniques such as electrospray (ESI) and matrixassisted laser desorption/ionization (MALDI) and the revival of time-of-¯ight analyzers created new opportunities for the characterization of polymers. In this review emphasis is put on MALDI time-of-¯ight mass spectrometry of polymers. The selection of an appropriate MALDI matrix, cationization salt and sample preparation techniques are critical success factors for obtaining a reliable mass spectrum and to infer structural information such as monomer mass(es) and end-groups. However even under optimized conditions mass discrimination in the analysis of polydisperse polymers and speci®c oligomer discrimination might occur. Hence hyphenated techniques such as size exclusion chromatography (SEC)/MALDI have been developed. Many different polymer applications appeared in recent literature, but most studies deal with homopolymers. Many challenges remain, particularly in the ®elds of halogenated polymers, polyole®nes, copolymers, blends, and in the sequencing of block-copolymers.