SummaryOn October 1989, eosinophilia and incapacitating myalgia, together with arthralgia, dyspnea, cough and edema of the extremities, were shown to be associated with L-tryptophan ingestion. Since then, 1531 cases of eosinophilia-myalgia syndrome have been reported in United States and 22 in Belgium.We report here the unusual pulmonary presentation of this syndrome with a dramatic response of eosinophilia to corticotherapy. The cardio-pulmonary symptoms of eosinophilia-myalgia syndrome and its pathophysiology, which remains unclear, are discussed.The withdrawal of the substance and corticotherapy generally lead to complete recovery although several deaths have been reported.