Hypercapnic respiratory failure due to L-tryptophan-induced eosinophilic polymyositis. A 24-year-old man presenting with fever, rash, and myalgias subsequently developed hypercapnic respiratory failure and severe limb muscle weakness. Muscle biopsy revealed eosinophilic myositis, due to the ingestion of large quantities of L-tryptophan as a dietary supplement. Complete recovery occurred with corticosteroid administration. Significant involvement of the respiratory muscles can be a predominant feature of this newly described disease entity. 