ABSTRACT Language comprehension proceeds at a very fast pace. It is argued that context influences the speed of language comprehension by providing informative cues. How syntactic contextual information influences the processing of incoming words is, however, less known. Here we employed a masked syntactic priming paradigm in four behavioural experiments in the German language to test whether masked primes automatically influence the categorisation of nouns and verbs. We found robust syntactic priming effects with masked primes but only when verbs were morpho-syntactically marked. Furthermore, we found that, compared to baseline, primes slow down target categorisation when the relationship between prime and target is syntactically incorrect, rather than speeding it up when the relationship is syntactically correct. This argues in favour of an inhibitory nature of syntactic priming. Overall, the data indicate that humans automatically extract syntactic features from the context to guide the analysis of incoming words during online language processing.