Pulmonary involvement in the eosinophilia-myalgia syndrome. We describe the cases of three women with pulmonary involvement in the eosinophilia-myalgia syndrome. The illness was characterized by elevated peripheral blood eosinophil counts, myalgias, fatigue, and dyspnea. Two of three patients had bilateral infiltrates on chest roentgenograms. All three had markedly decreased carbon monoxide diffusing capacities and pulmonary hypertension. High-dose prednisone therapy provided only partial resolution of the pulmonary symptoms. Open lung biopsy specimens showed chronic interstitial and perivascular infiltrates in two of the patients and moderate fibrointimal hyperplasia of pulmonary vasculature in the third. High-dose prednisone therapy prior to the biopsies may have modified the original histologic features. 