Abstract: The present invention relates to a method of predicting appearance after undergoing a medical procedure. The present invention may be utilised to assist a patient in deciding whether to undergo a procedure, or in selecting a particular procedure to produce a desired post-procedural appearance. The present invention identifies one or more precedent cases, where the same or a similar procedure was performed. These precedent cases are then analysed to calculate an observed change for each precedent case. The observed changes are then averaged to produce a final change function. This change function can then be applied to a pre-procedural model of the relevant body part of the patient, to produce a predicted post-procedural model of the patient's body part. In this way, the post-procedural appearance of the body part can be accurately predicted, based on a statistical analysis of historical data.