The paper comprises an investigation of the order of the main sentence elements (subject, verb, and object) in Greek stichic verse, and includes the first study of regular word order in Greek tragedy. It is shown that there is no consistent difference between poetic and prose texts in the order of subject, verb and object, so metre appears to have no visible effect on order. It is further shown that regularities in order do not have a purely syntactic explanation, but have a correlation with word size and with prosodic prominence, which may reflect cognitive constraints. It is proposed that the same holds generally in ancient Greek.