Newborn screening for cystic fibrosis (CF) was considered over 3 decades ago in 1970; however, the technology did not exist then for an accurate neonatal screening test. With the development of immunoreactive trypsinogen analysis, alone or coupled with DNA mutation analysis, the means were developed for CF newborn screening. Studies have demonstrated benefits of newborn screening in the areas of nutrition, cognitive function, pulmonary function, and survival.