BACKGROUND: Infective myositis is rare. The retrospective report of clinical data and symptoms from one patient with infective myositis will hopefully provide more information for clinicians in the diagnosis of this disease. METHODS: A male patient. 65 years old, was admitted with "fever and muscle pain since four days ago, accompanied by inertia of all limbs for one day", to the First Department of Neurology, Guangdong Provincial Hospital of Traditional Chinese Medicine on April 25(th,) 2005, Following admission, a history of diseases was record, and detailed physical and neurological examinations were performed. During the examination, symmetrical myasthenia appeared, tendon reflex disappeared, and creatine kinase levels were increased 500 times higher than normal. The patient was primarily diagnosed with hypokalemic periodic paralysis. myositis, Guillain-Barre syndrome, and Upper respiratory infection. Subsequently, the patient was treated with the following: cefuroxime for infection, potassium supplements, breviscapin for promoting blood circulation through the removal of stasis, and ATP/CO-A for myocardial nutrition. Antiviral drugs were not administered. However, laboratory samples were continuously monitored. Creatine kinase levels decreased to normal. and muscle pain was obviously relieved following antibiotics treatment. The results led to a final diagnosis of infective myositis. RESULTS : Four days after treatment (April 29(th)), Muscular tenderness and throat congestion were obviously improved (+/-). The neurological examination showed the patient was conscious, cooperated with treatment, and had normal intellect. No abnormalities of the cranial nerve were observed upon examination. Proximal and distal muscle strength and muscular tensions of the four limbs were all normal. Reflexes of the right biceps brachii muscle and its tendon were decreased, and knee tendon and Achilles tendon reflex were not induced. A Babinski reflex was not detected. The neurological examination presented no abnormalities, and the related creatine kinases were within normal range by re-examination at 2 weeks, and 1 and 3 months after discharge. CONCLUSION:A diagnosis of infective myositis should be considered for patients with clear prodromes of infection. that include symptoms of periodic paralysis and elevated creatine kinase levels. Treatment with sufficient antibiotics can obtain good results.