From a pediatric population of 10,000 there were a total of 292,750 visits to the pediatric service in a period of 10 years. This would also be the number of visits per 100,000 children per year. Telephone calls outnumbered all visits, at 300,000. After 20,000 physical examinations on admission and discharge in the newborn nursery. 90,000 well-baby visits including 75,000 immunizations accounted for approximately half of the office visits. There were 112,750 outpatient visits because of original illnesses, 40,000 return visits for acute illnesses and 30,000 return visits for chronic disorders, 15,000 consultations requested from other clinics, and 93,000 therapeutic injections. Nine thousand of these patients were admitted to the hospital (one admission per child by 10 years of age). There were 420 deaths between birth and 10 years of age, or 4.2%. Half of these were neonatal and half pediatric deaths. The necropsy rate was 95%. This clinical experience represents a horizontal view of a lifetime of pediatric practice in the antibiotic era. Parents should be taught to realize that each child has approximately 100 illnesses by the age of 10 years. These illnesses plus routine well-baby care and immunizations necessitate a minimum of 30 visits to the doctor. In the usual course of events the child will have a dozen different disorders requiring a doctor's attention. Almost every child will experience at least one hospital admission. Despite these hazards any infant who survives the newborn period in this antibiotic era faces only a 1% mortality before adolescence. All diagnoses were classified according to the Standard Nomenclature of Disease and code numbers reversed to give etiology precedence over topography. The total number of each disease was then recorded as incidence from birth to age 10 years per 10,000 children, or the incidence per 100,000 per year. This is a study of the incidence of diseases for which treatment was requested; not the true occurrence rate. The clinical load per year for a known pediatric population (determined from the number of births, school population, our office clinical records) can be compared or predicted for any disease by dividing the figures provided herein by the number of thousands of population and the number of years observed. Only the common cold and acute pharyngitis or tonsillitis occurred in every child. These common upper respiratory infections accounted for 40% of all illnesses, but only 8% of hospital admissions and no deaths. Twenty-one other disorders affected at least 10% of all children and accounted for an additional 36% of all outpatient morbidity, 38% of hospital admissions, 3.6% of neonatal deaths, 16% of pediatric deaths, but only 10% of all deaths. In order of frequency they were: otitis media, bronchitis, diarrhea, pyodermia, epidemic vomiting, herpangina, dental caries, conjunctivitis, cellulitis, furunculosis, acute fever of unknown origin, feeding problems, oxyuriasis, pneumonitis, hypochromic anemia, lacerations and abrasions, seborrheic dermatitis, measles, convulsions, and behavior disorders. Sixty-one diseases affected at least 1% of all children and accounted for an additional 19% of all illnesses seen in the outpatient clinic, 30% of hospital admissions, 7% of pediatric deaths, but only 3% of all deaths. There were no newborn deaths. (If uncomplicated prematurity which involves 7% of all children were included, 16% of neonatal deaths would also be accounted for.) In order of frequency these diseases were: Lymphadenitis, contact dermatitis, umbilical granuloma, exanthem subitum, acute sinusitis, infestation with chiggers, miliaria, allergic rhinitis, chickenpox, asthma, fissure in ano, lacerations, herpetic stomatitis, chronic tonsillitis, errors of refraction, eczema, fungus infections, intertrigo, pertussis, pyelonephritis, fracture, verruca vulgaris, diaper rash, tinea capitis, scabies, mumps, burns (first and second degree), dermatitis medicamentosa, malnutrition (under 2 years), thrush, primary tuberculosis, rubella, ascariasis, hordeolum, hernia, suppurative otitis media, infectious mononucleosis, influenza, poliomyelitis, urticaria, hemangiomata, abdominal pain (etiology unknown), scarlet fever, cranial stenosis, dental abscess, bronchiolitis, strabismus, contusions and hematomata, chronic sinusitis, food allergy, vulvovaginitis, atypical pneumonia, heart murmurs (incompletely diagnosed), chronic constipation, vomiting, laryngitis, molluscum contagiosum, laryngotracheobronchitis, erythema multiforme, animal bite, and complaints—no disease found. The other 454 diseases encountered affected less than 1% of all children and were responsible for less than 5% of the total morbidity. They were chiefly congenital anomalies, rare types of infections and new growths. Although numerically unimportant in office practice they accounted for 24% of hospital admissions and 79% of all deaths.