Lambert Eaton myasthenic syndrome (LEMS) is a rare neuromuscular junction disease. Often, the signs and symptoms of LEMS are mistaken for myasthenia gravis and therefore the workup is misdirected. A physician must look for an occult malignancy when the diagnosis is made and then continue to search for a malignancy for at least 5 years after diagnosis. The diagnosis of LEMS can be confirmed with electrophysiologic studies or with serum calcium channel antibodies. In most patients with LEMS, 3,4-diaminopyridine will improve strength. In patients without malignancy, immunosuppressants do have a role in the treatment of LEMS. Patients and physicians must be aware that certain situations and drugs may exacerbate weakness.