In two on-line experiments (N = 386) we asked participants to make speeded grammatical decisions to a mixture of syntactically correct sentences and ungrammatical sequences of words. In Experiment 1, the ungrammatical sequences were formed by transposing two inner words in a correct sentence (e.g., the brave daunt the wind / the daunt brave the wind), and we manipulated the orthographic relatedness of the two transposed words (e.g., the brave brace the wind / the brace brave the wind). We found inhibitory effects of orthographic relatedness in decisions to both the correct sentences and the ungrammatical transposed-word sequences. In Experiment 2, we further investigated the impact of orthographic relatedness on transposed-word effects by including control ungrammatical sequences that were matched to the transposed-word sequences. We replicated the inhibitory effects of orthographic relatedness on both grammatical and ungrammatical decisions and found that transposed-word effects were not influenced by this factor. We conclude that orthographic relatedness across adjacent words impacts on processes involved in parallel word identification for sentence comprehension, but not on the association of word identities to positions in a sequence.