It is not clear a priori how well parsers trained on the Penn Treebank will parse significantly different corpora without retraining. We carried out a competitive evaluation of three leading treebank parsers on an annotated corpus from the human molecular biology domain, and on an extract from the Penn Treebank for comparison, performing a detailed analysis of the kinds of errors each parser made, along with a quantitative comparison of syntax usage between the two corpora. Our results suggest that these tools are becoming somewhat over-specialised on their training domain at the expense of portability, but also indicate that some of the errors encountered are of doubtful importance for information extraction tasks.