Oral examinations tend to be feared more than the written ones and the PhD viva is perhaps no exception. There is, however, no reason to be scared of the viva. Some anxiety is only natural, and shows that you care, but it is important not to let your nerves get the better of you. The best way to do this is to understand the purpose of the viva and to be well prepared. I briefly explained the viva in the earlier article: The PhD viva voce. To summarise, though, the point of the viva is to give you the opportunity to defend your thesis. It is not a stand alone examination and you cannot be passed or failed solely on your viva performance.
If your written thesis is good enough then the examiner may have already decided to pass your thesis even before you set foot in the viva. Submitting a well-written, coherently argued thesis, and having confidence in your argument goes a long way in preparing for the viva that follows. Beyond that, there are a number of things you can do to help you prepare:
If you find that you need additional help to prepare for your viva, the PhD Consultancy offers all level of support for viva preparation.