Frequency and characteristics of the genetic disease in a pediatric hospital1 'equency and characteristics of patients discharged with recoyn zed genetic diseases by current technical literature available in 1988 (GDI from a pediatric hospital at Santiago, Chile, are described. On the last three months of year 1983, a prospective study on 2,987 hospital admissions corresponding to 1,196 patients was done. Prevalence and incidence of GD were 62.5% and 17% among hospital acmissions as a whole and 49.75% and 47.7% respectively when only individual patients were considered. No sex di f ferences were found between patients with and without GD, but the frequency of GD was significantly higher in patients staying 7 or more weeks in hospital (12% vs. 3.4%), as among those who required two or more admissions (10.9% vs. 4.3%) or were refered from outside metropolitan Santiago (37.3% vs. b.1%). hirst ten more frequent GD, in decreasing order of importance, were cardiac malformations, leukemias, cleft lip and/or palate, congenital dislocation of the hip, epilepsy and convulsions, idiopathic scoliosis, Down's syndrome, anal malformations, aganglionic megacolon and cystic fibrosis. The importance of diseases with genetic background is thus emphasized in a pediatric hospital.