This monograph written in Spanish is a more complete account (6 observations on children and 3 on adults) of a new symptom complex first reported by the author in 1939. The condition consists of fever, catarrh and adenopathy with 30,000 to 70,000 white cells, of which 80 per cent are eosinophils. There is also a granulation of lung tissue, which is shown in illustrative roentgenograms. The bone marrow shows a hyperplasia of eosinophilic forms, as do the lymph nodes. The disease has a tendency to recovery in two years. No good etiologic factor was found.