A 52-year-old man presented with unilateral left periorbital and frontotemporal pain associated with a partial ipsilateral Horner's syndrome of the postganglionic type and representing a pericarotid syndrome. MRI demonstrated a perivascular subacute hematoma at the level of the cervical portion of the left internal carotid artery with a markedly reduced flow-void signal. MR angiography confirmed the narrowed lumen of the dissected cervical internal carotid artery. There was also a right-sided precavernous carotid aneurysm. Three months later the left-sided pain had subsided, with complete resolution of the hematoma and incomplete restoration of the left carotid lumen seen on MR angiography. Dissection of the carotid wall may cause the oculosympathetic paralysis by producing a lesion of the superior cervical ganglion, the internal carotid nerve, or the perivascular sympathetic plexus. Whereas in pericarotid syndrome the most common cause is cervical carotid dissection, Raeder's syndrome additionally involving parasellar cranial nerves, may be caused by any paracavernous/cavernous lesion, including neoplasms and intracranial carotid aneurysms. The clinical distinction is useful to determine the appropriate diagnostic investigation, in view of the different pathoanatomical localization and different disease spectrum. As demonstrated in the present case, the combination of MRI and MR angiography is a reliable noninvasive tool to investigate the differential diagnosis of pericarotid syndrome, accurately depicting occlusive, stenotic or aneurysmal lesions of the carotid artery. We suggest that intraarterial angiography is no longer necessary.