Diagnostic ultrasonography (A-and B-scans) and X-ray computer tomography are completely different in their physical bases. The yield, therefore, different informations in the examination of space-space-occupying lesions in the orbit. The informations which can be recorded from normal and pathologic tissues in the orbit are described in this paper. The value, but also the limitations, of the various diagnostic methods are demonstrated in clinical cases. The reliable diagnosis of unilateral, progressive pseudoprotrusion in high myopia by ultrasound exophthalmometry is described. Facilities and diagnostic value of ultrasonography and X-ray computer tomography in the localisation of orbital tumours and in the determination of their relationship to the orbital walls are discussed. The diagnostic management in intermittent exophthalmos, in orbital abscess and in Grave's disease is reported. The complete ophthalmic examination is followed by ultrasound exophthalmometry and--if indicated--A- and B-scan ultrasonography of orbital tissues. Computed X-ray tomography is indicated in all tumour-suspicious lesions within the orbit. The results of diagnostic ultrasonography and computed X-ray tomography may complete each other in a very helpful manner. The combined evaluation yields better results than the use of only one of these methods. In orbital varices we recommend, to supplement ultrasonography by venography and eventually arteriography. In diagnoses of orbital abscesses resulting from paranasal sinusitis it may usually suffice to combine ultrasound diagnosis with native X-ray examinations. Good interdisciplinary cooperation in diagnosis and therapy is mandatory in all patients with space-occupying orbital lesions.