The diagnostic work-up of patients with third cranial nerve palsy includes neuroimaging because the lesion of the oculomotor nerve may result from compression due to an aneurysm. The advantages and disadvantages of different neuroimaging techniques, i. e. magnetic resonance angiography (MRA), computed tomography angiography (CTA) and intra-arterial digital subtraction angiography (DSA), are still under debate. In this context, the present case report demonstrates that the application of 3 Tesla-MRA may help to detect an aneurysm of the internal carotid artery which had remained undetected by non-invasive standard methods applied before. Therefore 3 Tesla-MRA may help to fill a gap in diagnostic approaches between non-invasive (MRA, CTA) and invasive (DSA) neuroimaging techniques.