Abstract: REPORTS on intra-orbital tumours and causes of exophthalmos do not mention the disease entity ofeosinophilic granuloma first described by Lichtenstein and Jaffe (1940).Pfeiffer (1943), in reviewing 200 successive cases of exophthalmos, enumerated 31 different lesions, among which eosinophilic granuloma of the orbit was not listed.Forest (1949) reported on 222 cases of intra-orbital tumours collected from the registry of the U.S. Army Institute of Pathology, but did not include eosinophilic granuloma.Dandy (1941) did not mention this possibility in his monograph on orbital tumours.A review of the literature on eosinophilic granuloma of the bone (Dundon and others, 1946; Hansen, 1949; Jaffe and Lichtenstein, 1944) revealed one case in which the lesion was limited to the orbit (Walthard and Zuppinger, 1949).Here the diagnosis of a granuloma, probably due to xanthomatosis, was made in a two-year-old boy, but a re-check confirmed the correct diagnosis of eosinophilic granuloma.This report seems justified by the need to call attention to this lesion in the differential diagnosis of intra-orbital tumours. CASE REPORTCase 1. M. S., a 14-year-old boy, came to the Ophthalmological Clinic on January 8, 1950, complaining of pain in the left supra-orbital region, and blurred vision of two weeks' duration in the left eye.Two weeks previously the patient had been hit in the head (left temporal region) by the iron door of a bus while trying to board the moving vehicle.The family history as well as the past history were irrelevant, except for the fact that the boy had spent the last four years in an institution for defective children because he was mentally retarded.In 1944 he had suffered from a chronic otitis media in the left ear.On inspection the boy was seen to keep his left eye closed.There was no swelling of the lids nor any external sign of contusion.On being told to open and close his left eye he was able to do so quite freely.