Sang Woo Han. 2001. An SIOV Hypothesis for Old English. Studies in Modern Grammar 24, 161-177. Both the single SOVI hypothesis and double-underlying structure hypothesis do not explain various syntactic patterns of Old English. However, we can be derived them from SIOV underlying structure using the optional verb movement rule. By assuming I-initial hypothesis, we don`t need to assume the NP raising rule any more. Therefore, it can be said that this SIOV underlying structure hypothesis is a more economical and desirable hypothesis than the SOVI hypothesis and double-underlying structure hypothesis because it needs just one movement in explaining various word order types which can be found in Old English manuscripts. In spite of its merit, however, the SIOV hypothesis seems to have a critical problem. When INFL is in medial position, the verb has to move to INFL, and the surface order derived from the SIOV underlying structure would not be SOV but SVO order. It contrasts with the predominating theory that Old English is an SOV language. It is very difficult to explain all the syntactic structures with current theoretical methods. As a conclusion, it could be said that it would be more desirable to study syntactic patterns of Old English by analysing Old English manuscripts than by using current theories.