Age estimation of unaccompanied minors is an issue that occasionally demands forensic assessment. There is currently significant disparity between diagnostic procedures used in Spain. The aim of this document is to standardise and harmonise the minimum technical requirements of expert reports, and how the standard deviation due to normal distribution as well as how the variability in individual physical development should be handled. The proposals include making this kind of study by experienced and supervised staff of Forensic Institutions, following informed consent of the presumed minor. Evaluation must consist of an interview, with a physical examination, radiological examination of the wrist, and dental pantomography. Radiological or computerized tomography of the proximal epiphysis of the collar bone might be done in particular cases. It is also recommended that the Courts make the decision on whether the person is a minor or not.