Polyamide 6 (PA6) is a semi-crystalline, polar thermoplastic and one of the most important engineering plastics due to its good mechanical and chemical properties in combination with different additives. When absorbing water, nearly all properties of a PA6 will change. This is the so called plasticizing effect of water and it is well known for most of the mechanical properties. These changes are reversible, as long as PA6 is not damaged through hydrolysis. However, considering the fracture behavior and the energy absorption of PA6, this conclusion is not totally clear. The interaction between different media and polyamide can be analyzed in more detail by the use of the method of EWF in comparison to determine the tensile test behavior. To examine this aspect in more detail, the method of essential work of fracture (EWF), which is well established for analyzing the fracture mechanics of ductile materials, is selected in this investigation. The method of EWF is a concept of elastic plastic fracture mechanics and was first described by Broberg. The study on thin PA6 films demonstates that the fracture behavior of PA6 is different for different media. Furthermore, the crack initiation process is weakly influenced, whereas the crack propagation process is strongly influenced, by a media uptake.