Existing models of short-term sequence memory can account for effects of long-term knowledge on the recall of individual items, but have rarely addressed the effects of long-term sequential constraints on recall. We examine syntactic constraints on the ordering of words in verbal short-term memory in four experiments. People were found to have better memory for sequences that more strongly conform to English syntax, and that errors in recall tended to make output sequences more syntactic (i.e., a syntactic bias). Model simulations suggest that the syntactic biasing in verbal short-term recall was more likely to be accounted for by a redintegration mechanism acting over multiple items in the sequence. The data were less well predicted by a model in which syntactic constraints operate via the chunking of sequences at encoding. The results highlight that models of short-term memory should be extended to include syntactic constraints from long-term representations—most likely via redintegration mechanisms acting over multiple items—but we also note the challenge of incorporating such constraints into most existing models.