This paper discusses the influence of stationary (non-fluctuating) noise on processing and understanding of sentences, which vary in their syntactic complexity (with the factors canonicity, embedding, ambiguity). It presents data from two RT-studies with 44 participants testing processing of German sentences in silence and in noise. Results show a stronger impact of noise on the processing of structurally difficult than on syntactically simpler parts of the sentence. This may be explained by a combination of decreased acoustical information and an increased strain on cognitive resources, such as working memory or attention, which is caused by noise. The noise effect for embedded sentences is less than for non-embedded sentences, which may be explained by a benefit from prosodic information.