Diseases that can clinically simulate an uveitis are summarised under the name Masquerade syndromes. They constitute a heterogenous group of malignant and non-malignant entities that must be excluded in the differential diagnosis. Of the malignant diseases lymphomas are only rarely observed as the cause of a pseudo-uveitis, whereas especially leukaemic diseases and, in childhood, retinoblastomas and the extremely rare intraocular medulloepithelioma must be excluded. Of the non-malignant diseases in childhood, besides Coats' disease, a juvenile xanthogranuloma as well as persisting hyperplastic primary vitreous body should also be considered as the cause of an atypical uveitis. Systemic diseases such as tuberous sclerosis or neurofibromatosis are usually diagnosed in good time by means of the accompanying symptoms. In case of doubt in childhood, an examination under anaesthesia and, if necessary, further imaging diagnostics should be performed in order to avoid with certainty a false diagnosis having possibly serious consequences.