Because of the variably modifiable material qualities, plastics are used in every area of life nowadays. Thereby, the polymers have to meet various requirements to be able to guarantee the suitability for the use of the respective components. Besides, during their operation time the plastics are exposed to steadily changing environmental influences, which lead to the aging of the polymers. Frequent temperature changes, dampness, saline media and mechanical loads belong to it among others. The aging effects, caused by the interaction with the surrounding media, are not quantifiable to detect in the components applications. Strength losses, changes in the material behavior, for example embrittlement, or a degradation of the molecular weight resulted from the aging process, can only be detected after the components’ failure. To be able to prove these qualities in aged plastic components, besides, destroying testing methods are necessary, so that the checked components cannot be used anymore and are to be exchanged, in any case. Hence, in the following a measuring procedure will be introduced, with which aging effects in plastics can be non-destructively detected. In addition, polyamide 6 specimens are aged hygrothermal artificially and their macromolecular changes are made visible by means of ultrasonic testing.