The southbound carriageway between the A423 (Hinksey) and A415 (Marcham) opened just after 3pm.
The incident happened just after 4.10am today (Thursday) which caused a full closure of the A34 southbound.
The lorry has been recovered but there are still minor delays in the area.
The Highways Agency provides live traffic information via its website, local and national radio travel bulletins, electronic road signs and mobile platforms, such as the iPhone.
Members of the public should contact the Highways Agency Information Line on 0300 123 5000.
Journalists should contact the Highways Agency press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.
Published 26 February 2015