Recent reviews of respiratory-tract affections caused by M. pneumoniae under- score the benign and often subclinical course of the infection. Severe pneumonia with a reticular or acinar pattern is certainly unusual and a fatal outcome is rare, but the incidence of both is underestimated. Erythromycin and tetracyclines are the first-choice antibiotics. There is evidence indicating the importance of im- munopathogenic mechanism in provoking pneumonia and even respiratory failure. REFERENCES 1. Krech U, Price PC, Jung M: The laboratory diagnosis and epidemiology of mycoplasma pneumoniae in Switzerland. Infection 4:33, 1976. 2. Fischman RA, Marschall KE, Kislak JW: Adult respiratory distress syndrome caused by mycoplasma pneumoniae. Chest 74:471, 1978. 3. Reigner Ph, Domenighetti G, Feihl F, Bonjour JPh, Perret CI: Syndrome de detresse respiratoire aigu sur infection a mycoplasme. Sch Med W 110:220, 1980. 4. Kaufman JM, Cuvelier CA, Van der Straeten M: Mycoplasma pneumonia with fulminant evolution into diffuse interstitial fibrosis. Thorax 35:140, 1980. 5. Murray HW, Masur H, Senterfit L, Roberts R: The protean manifestations of mycoplasma pneumoniae infection in adults. Am J Med 58:229, 1975. 6. Levine DP, Lerner AM: The clinical spectrum of Mycoplasma pneumoniae infections. Med Clin N Am 62:961,1978. 7. Twomey JA, Espir ML: Neurological manifestations and Mycoplasma pneumoniae infection. BMJ 2:832, 1979. 8. Kingston JR, Chankock RM, Mufson MA, Hellman LP, James WD, Fox HH, Mankoma C, Boyers J: Eaton agent pneumonia. JAMA 176:118, 1961.