Myasthenia gravis is the most common disease of neuromuscular transmission; however, it may be difficult to diagnose in the elderly patient with comorbid illnesses and vague symptoms. We report two cases of myasthenia gravis in elderly women, in whom the initial diagnosis of ischemic stroke by neurologists was inaccurate; radiographic evidence of stroke was considered confirmatory. In light of the high prevalence of silent cerebrovascular disease in elderly patients, incidental neuroimaging findings may mislead clinicians. Current aggressive therapies, including thrombolysis, can cause significant morbidity in patients whose condition is misdiagnosed as stroke. Although myasthenia gravis most commonly occurs in younger people, 13 to 20% of all patients with this disease are in the seventh decade of life or beyond. When faced with new-onset weakness in an elderly patient, particularly of cranial musculature, clinicians should consider myasthenia gravis as a diagnostic possibility.