Vertical stability following maxillary downgrafting in cleft patients is poor with an average relapse of 42 per cent (ranged 0-100 per cent). Overcompensation should, therefore, be undertaken with 2 mm added to the downgraft movement for bony relapse and 1 mm added to the downgraft movement for upper lip lengthening. The Tideman et al. method for advancement of the lesser maxillary segment is a very stable procedure (less than 8 per cent relapse). Semi-rigid fixation with plates, bone grafting and 'ramping' enhances stability; and freeway space assessment preoperatively is an important guide to relapse potential in the downgrafted cleft maxilla. All surgical prediction tracings should be done with the patient at the occlusal vertical dimension to prevent inadequate maxillary advancement and subsequent reverse overjet or excessive anterior incisor proclination developing with vertical relapse.