Background & Aim: The natural course of unruptured vertebral artery dissecting aneurysms (VADAs) remains unclear. The purpose of this retrospective study was to develop a strategy for treating unruptured VADAs based on a long-term follow-up.Methods & Materials/Patients: Our study population consisted of 100 patients with unruptured VADAs; in 66 patients, the initial symptom was only headache, 30 patients presented with ischemic symptoms, and 4 patients presented with mass effect. All patients underwent magnetic resonance imaging and magnetic resonance angiography at the time of admission, and at the intervals of 2 weeks and 1, 3, 6, 12, and 24 months. If the dissection site was demonstrated to be enlarged on magnetic resonance imaging and magnetic resonance angiography without the manifestation of new symptoms, the patients received additional treatment to prevent bleeding.Results: Of the 30 patients, 4 underwent early intervention because of symptom exacerbation. The other 96 were initially treated conservatively; during the follow-up, 5 manifested lesion enlargement on magnetic resonance angiography. Nine patients received additional treatment; 1 underwent direct surgery with the trapping of the dissection site, and 8 underwent coil embolization. The other patients continued to be treated conservatively; the dissection length remained unchanged in 22, improved or healed in 5 patients, and disappeared in 1 patients. We treated patients with recurrent ischemic attacks with antiplatelet therapy. None of the patients experienced bleeding or permanent neurological deficits during the follow-up.Conclusion: The nature of an unruptured VADA is not highly aggressive. However, if the dissection site enlarges without the manifestation of new symptoms, it should be occluded. In patients with recurrent ischemic attacks, antiplatelet therapy should be considered.