Between the polymerisation stage and the machine hopper, plastic pellets can absorb moisture at many points - for example during pelletisation, conveying and storage. Comparative studies have shown that only the Karl Fischer titration method can provide a reliable value for low pellet moisture contents. Thermogravimetric methods, on the other hand, measure the evaporation losses of all volatile substances, not just moisture, and therefore give much higher values. Finally, a new method for determining the increase in internal pellet moisture content during immersion in water is described and information is provided on how to obtain samples with a defined moisture content.