If you leave your employment without providing your employer with the relevant notice as required under your contract of employment, then you are in breach of your contract. (Have you checked your contract to see what your notice period is?) I would say it largely depends on the nature of you role as to whether an employer would go to the trouble and expense of taking any action against you. If you hold a senior position and your leaving abruptly would leave your employer in a difficult position (eg, loss of reputation/loss of goodwill/loss of clients) they might take action against for you their losses (not only losses to the business but expenses incurred in, for instance, hiring a locum at short notice and at a higher salary). If, on the other hand, you hold a more junior position which could be temporarily covered by colleagues if you left without notice, an employer would be unlikely to take any action (unless they are particularly vindictive, but only you would know that). It always pays to try and leave on a good note though so if it really is necessary for you to leave without notice, have a chat with your boss first to explain the situation. They may not like what you are doing but at least they might understand why.