We identified eight patients (six women and two men) who had pulmonary infiltrates during treatment with minocycline hydrochloride between 1989 and 1992 in French referral centers for drug-induced pulmonary diseases. Clinical files, chest roentgenograms, computed tomographic scans, pulmonary function, and bronchoalveolar lavage data were reviewed. Minocycline treatment was given for acne (n = 4), genital infection (n = 3), and Lyme disease (n = 1). The duration of treatment averaged 13 +/- 5 days (mean +/- SE); the total dose, 2060 +/- 540 mg. Patients presented with dyspnea (n = 8), fever (n = 7), dry cough (n = 5), hemoptysis (n = 1), chest pain (n = 2), fatigue (n = 3), and rash (n = 3). Chest roentgenograms showed bilateral infiltrates in all cases. Pulmonary function was measured in five patients; four had airflow obstruction and two had mild restriction. Blood gas tests demonstrated hypoxemia in seven patients (58 +/- 3 mmHg). Seven patients had blood eosinophilia (1.76 +/- 0.2 x 10(9)/L). Bronchoalveolar lavage (performed in seven patients) showed an increased proportion of eosinophils (0.30 +/- 0.07). The Cd4+/CD8+ ratio was determined in four cases and was low in three. Transbronchial lung biopsy, performed in two patients, showed interstitial pneumonitis in both patients, with marked infiltration by eosinophils in one patient. The outcome was favorable in all patients. Because of severe symptoms, steroid therapy was required in three patients. Rechallenge was not attempted. We conclude that minocycline can induce the syndrome of pulmonary infiltrates and eosinophilia, that presenting symptoms may be severe and may culminate in transient respiratory failure, and that the disease has a favorable prognosis.