Goodpasture's syndrome can be cited as a good example of new orientation in the clinical utilization of advanced knowledge and technique. Purposeful research and logically interpreted clinical observations during the past two decades have brought about not only clearer understanding of the pathogenic mechanism of this condition but also its more successful treatment. In typical cases the onset is signalized by symptoms and signs referable to the respiratory tract, although in rare instances renal manifestations may precede pulmonary disease. The latter may begin with bouts of nonproductive cough, likely to be followed by recurrent hemoptysis or subsequent massive pulmonary hemorrhage. Also, the patient may complain of progressive, sometimes distressing dyspnea. Too, low-grade fever, easy fatigability, loss of appetite and loss of weight, pronounced weakness and pallor may be noted. X-ray evidence of lung involvement may be present when the patient is first seen or when he is observed during exacerbation of the disease. One may note unilateral, bilateral, diffuse or localized changes, such as nodular, linear, ill-defined mottled, veil-like, woolly or dense homogeneous shadows which are either perihilar, peripheral or limited to one lobe. There may be enlargement of hilar lymph nodes. The pulmonary changes are sometimes ephemeral. They may clear within few days or weeks without specific treatment. Increased interstitial reticular markings may be observed between hemorrhagic episodes. Simultaneous or subsequent renal involvement may be associated with dark-brown or reddish discoloration of the urine or with frank hematuria, oliguria or anuria. Laboratory findings establish the diagnosis of glomerulonephritis. In 1940, Chikamitsu (Folia Endocrin Jap 16:85, 1940) made significant contributions to the understanding of the pathogenesis of Goodpasture's syndrome. He produced glomerulonephritis in rabbits by injection of anti-rabbit-lung serum and also, of anti-rabbit-kidney serum. Eisen et al (J Immunol 65:543, 1950) ascertained experimentally the antigenic similarities between pulmonary alveolar basement membrane and renal glomerular basement membrane. To Coons et al (J Exper Med 91:1, 1950 and 102:49, 1955) belongs the credit for the method of chromatic visualization of antigen-antibody complexes with the aid of fluorescent material. In 1955, Parkin et al (Am J Med 18:220, 1955) proposed the assumption that hypersensitivity might have a major role in the combined occurrence of recurrent pulmonary hemorrhages and nephritis. Subsequently several clinical and research studies supported the possibility of anti-lung antibody production due to a certain type of pulmonary disease which, in turn, induces glomerulonephritis. Others hypothesized an opposite train of events, namely that severe inflammatory damage to renal glomeruli leads to liberation of antibodies which exert destructive influence upon pulmonary alveoli. A number of cases are on record in which pulmonary hemorrhage ceased following bilateral nephrectomy, the patient remaining symptom-free after renal transplantation. Some investigators assert that a common antigen exists in the basement membrane of pulmonary alveoli and of the renal glomeruli. With these views in mind, it seems permissible to look upon Goodpasture's syndrome as a bipolar clinical entity in which either the kidneys or the lung may be the primary site of pathologic manifestations, with reciprocal involvement of other structures as the disease spreads. The immunologic aspects of this syndrome are being used in its diagnosis. Immunofluorescence microscopy is likely to reveal striking linear basement membrane fluorescence of heavy deposition of immunoglobulin G and beta 1-C globulin in renal biopsy specimens. Lemer et al (J Exper Med 126:989, 1967) and McPhaul et al (J Immunol 103:1, 168, 1969) reported the simultaneous presence of circulating and fixed antibodies to glomerular basement membrane in cases of Goodpasture's syndrome. Lung biopsy and fluorescence microscopy may reveal linear deposition of immunoglobulin G and beta 1-C globulin along the basement membrane of alveolar septa. Current treatment of Goodpasture's syndrome is based on pertinent immunologic concepts. It consists of separate, combined or coordinated administration of corticosteroids (prednisone, prednisolone), immunosuppressive agents (azathioprine, mercaptopurine), peritoneal dialysis, hemodialysis, bilateral nephrectomy and renal transplantation. Even though competent reports are discordant relative to therapeutic results, the outcome of the disease is not considered inexorably fatal. The prognosis depends on the type and severity of the primary causal agent, the gravity of the condition when the patient is first seen, on his innate resistance, defense and repair capabilities, and on the promptness of optimal treatment.