To assess the natural history, pathogenesis, and treatment modalities of symptomatic bilateral middle cerebral artery stenosis, we retrospectively evaluated a consecutive series of patients for their medical history, anamnesis, and our treatment protocol. Treatment included transluminal angioplasty, bypass surgery and/or conservative antiplatelet therapy for prevention of the stroke attack and vessel reconstruction. Indications, feasibility, effectiveness, and complications of treatment are also discussed. A series of 19 patients with symptomatic bilateral middle cerebral artery (MCA) stenosis were treated consecutively from 1998 to 2002. Medical history, anamnesis, and treatment protocol were reviewed and evaluated retrospectively, Of these 19 patients, six (six vessels, 31.57%) were treated by balloon (two vessels) or stent-assistant angioplasty (four vessels), four (four vessels, 21.05%) were treated by bypass surgery, 18 vessels plus ten vessels occluded before treatment (47.37%) were conservatively treated by antiplatelet agents. 24 vessels (12 patients) were followed from three months to four years by angiography (nine cases), TCD (12 cases), or MRA (five cases). A total of 38 vessels were involved (19 vessels), of which ten vessels (10/38, 26.31%) had occluded before coming to our hospital. Three patients (3/19, 15.78%) had a history of hypertension, five had a history of smoking. The mean age of these 19 patients was 33 yrs (24 similar to 42 yrs), with a slight male preponderance (males/females = 13/6). Initial clinical presentations were TIAs (14/19, 73.68%) and minor stroke (5/19, 26.32%), symptoms attacked alternatively for five patients (5/38, 13.16%). Seven vessels (7/28, 25%) occluded within one to three years, of which three occluded asymptomatically, four acutely occluded vessels accompanied acute stroke. Nine vessels (9/28, 32.14%) were treated by conservative antiplatelet agents and one treated by bypass surgery had related recurrent TIAs. Vessels treated by angioplasty (balloon or stent) remained patent and free of symptoms. The stenosed bilateral MCA may occlude within one to three years without intervention. The pathogenesis of this special disease is unclear; it may be genetic or due to asymptomatic infection. The results showed that earlier appropriate treatment can resolve the clinical symptoms and somehow change the natural history of this disease. Conservative medical therapy cannot prevent further stroke attack. Collaterals are very important for these special patients.