OWL is recognized as the de facto standard notation for on- tology engineering. The Manchester OWL Syntax (MOS) was developed as an alternative to symbolic description logic (DL) and it is believed to be more e ective for users. This paper sets out to test that belief from two perspectives by evaluating how accurately and quickly people understand the informational content of axioms and derive inferences from them. By conducting a between-group empirical study, involving 60 novice participants, we found that DL is just as e ective as MOS for people's understanding of axioms. Moreover, for two types of inference problems, DL supported signi cantly better task performance than MOS, yet MOS never signi cantly outperformed DL. These surprising results suggest that the belief that MOS is more e ective than DL, at least for these types of task, is unfounded. An outcome of this research is the suggestion that ontology axioms, when presented to non-experts, may be better presented in DL rather than MOS. Further empirical studies are needed to explain these unexpected results and to see whether they hold for other types of task.