Temporalis fascia, placed as an underlay graft, is commonly used to repair tympanic membrane perforations. Graft failure, however, is a well recognized complication. Grafts are often allowed to dry out during the procedure and, therefore, are often positioned in a dry or partially dehydrated state and only become fully rehydrated after placement. This study looked at how the size of the temporalis fascia alters with its state of hydration. The size of 20 temporalis fascia grafts was measured when fresh, after flattening and allowing them to dry, and finally after rehydrating the grafts with 0.9 per cent saline solution. Significant shrinkage was demonstrated. It is therefore proposed that a cause of increased failure rates, particularly in anterior myringoplasties, is loss of underlay due to graft rehydration and shrinkage. Thus graft shrinkage should be considered when positioning the graft.